Initial commit

- tokenizing, parsing and basic eval support
    - arithmetic (+, -, *, /)
    - quote
    - atom for checking if the arg is an atom (i.e. not a list)
    - eq for checking equality
    - > for checking order
    - if
- some unit testing
- simple repl
- mem management needs improvement :-)

17 files changed, 2287 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..5761abc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+*.o
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..f53a3f0
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,27 @@
+SOURCES = parse.c list.c atom.c eval.c tokens.c
+OBJECTS = $(SOURCES:.c=.o)
+
+CFLAGS = -Wall -g
+LDFLAGS =
+
+CC = gcc
+LD = gcc
+
+# ifneq ($(BUILD_TEST),)
+
+test: CFLAGS := $(CFLAGS) -DBUILD_TEST
+test: $(OBJECTS) tst_main.o
+	$(LD) $(LDFLAGS) -o $@ $^
+
+# else
+
+repl: $(OBJECTS) repl.o linenoise.o
+	$(LD) $(LDFLAGS) -o $@ $^
+
+# endif
+
+.PHONY: clean
+clean:
+	rm -f *.o
+	rm -f test
+	rm -f repl
diff --git a/atom.c b/atom.c
new file mode 100644
index 0000000..73ecd7e
--- /dev/null
+++ b/atom.c
@@ -0,0 +1,100 @@
+#include "atom.h"
+#include "list.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+struct atom true_atom;
+struct atom false_atom;
+struct atom nil_atom;
+
+struct atom *atom_new(char type)
+{
+    struct atom *atom = calloc(1, sizeof(*atom));
+    atom->type = type;
+    return atom;
+}
+
+struct atom *atom_new_int(long l)
+{
+    struct atom *atom = atom_new(ATOM_INT);
+    atom->l = l;
+    return atom;
+}
+
+struct atom *atom_new_str(const char *str, int len)
+{
+    struct atom *atom = atom_new(ATOM_STR);
+    atom->str.str = strndup(str, len);
+    atom->str.len = len;
+    return atom;
+}
+
+struct atom *atom_new_sym(const char *sym, int len)
+{
+    struct atom *atom = atom_new_str(sym, len);
+    atom->type = ATOM_SYMBOL;
+    return atom;
+}
+
+struct atom *atom_new_list(struct list *list)
+{
+    struct atom *atom = atom_new(ATOM_LIST);
+    atom->list = list;
+    return atom;
+}
+
+#ifdef BUILD_TEST
+
+#include "test_util.h"
+
+TEST(atom_new)
+{
+    struct atom *atom = atom_new(ATOM_STR);
+    ASSERT_TRUE(atom != NULL);
+    ASSERT_EQ(ATOM_STR, atom->type);
+}
+
+TEST(atom_new_int)
+{
+    struct atom *atom = atom_new_int(42);
+    ASSERT_TRUE(atom != NULL);
+    ASSERT_EQ(42, atom->l);
+}
+
+TEST(atom_new_str)
+{
+    struct atom *atom = atom_new_str("foobar", 6);
+    ASSERT_TRUE(atom != NULL);
+    ASSERT_STREQ("foobar", atom->str.str);
+
+    atom = atom_new_str("foobar", 3);
+    ASSERT_TRUE(atom != NULL);
+    ASSERT_STREQ("foo", atom->str.str);
+
+    ASSERT_EQ(ATOM_STR, atom->type);
+}
+
+TEST(atom_new_sym)
+{
+    struct atom *atom = atom_new_sym("foobar", 6);
+    ASSERT_TRUE(atom != NULL);
+    ASSERT_STREQ("foobar", atom->str.str);
+
+    atom = atom_new_sym("foobar", 3);
+    ASSERT_TRUE(atom != NULL);
+    ASSERT_STREQ("foo", atom->str.str);
+
+    ASSERT_EQ(ATOM_SYMBOL, atom->type);
+}
+
+TEST(atom_new_list)
+{
+    struct list list;
+    struct atom *atom = atom_new_list(&list);
+    ASSERT_TRUE(atom != NULL);
+    ASSERT_EQ(&list, atom->list);
+    ASSERT_EQ(ATOM_LIST, atom->type);
+}
+
+#endif
diff --git a/atom.h b/atom.h
new file mode 100644
index 0000000..3b716fa
--- /dev/null
+++ b/atom.h
@@ -0,0 +1,57 @@
+#ifndef ATOM_H
+#define ATOM_H
+
+#define LIST_GET_ATOM(LIST) ((struct atom *) (LIST)->data)
+
+#define ATOM_TYPE(LIST) ((LIST_GET_ATOM(LIST))->type)
+#define IS_INT(LIST) ((ATOM_TYPE(LIST)) == ATOM_INT)
+#define IS_STR(LIST) ((ATOM_TYPE(LIST)) == ATOM_STR)
+#define IS_SYM(LIST) ((ATOM_TYPE(LIST)) == ATOM_SYMBOL)
+#define IS_LIST(LIST) ((ATOM_TYPE(LIST)) == ATOM_LIST)
+
+#define IS_TRUE(LIST) (LIST_GET_ATOM(LIST) == &true_atom)
+#define IS_FALSE(LIST) (LIST_GET_ATOM(LIST) == &false_atom)
+#define IS_NIL(LIST) (LIST_GET_ATOM(LIST) == &nil_atom)
+
+#define CAR(LIST) LIST
+
+#define CDR(LIST) ((LIST) != NULL ? (LIST)->next : NULL)
+#define CDDR(LIST) CDR(CDR(LIST))
+
+enum
+{
+    ATOM_NIL,
+    ATOM_INT,
+    ATOM_STR,
+    ATOM_SYMBOL,
+    ATOM_LIST
+};
+
+struct atom
+{
+    union
+    {
+        long l;
+        struct
+        {
+            char *str;
+            int len;
+        } str;
+        struct list *list;
+    };
+    char type;
+};
+
+struct list;
+
+struct atom *atom_new(char type);
+struct atom *atom_new_int(long l);
+struct atom *atom_new_str(const char *str, int len);
+struct atom *atom_new_sym(const char *sym, int len);
+struct atom *atom_new_list(struct list *list);
+
+extern struct atom true_atom;
+extern struct atom false_atom;
+extern struct atom nil_atom;
+
+#endif
diff --git a/eval.c b/eval.c
new file mode 100644
index 0000000..43e1e05
--- /dev/null
+++ b/eval.c
@@ -0,0 +1,291 @@
+#include "eval.h"
+#include "list.h"
+#include "atom.h"
+#include "parse.h"
+
+#include <string.h>
+
+static int atom_cmp(struct list *a, struct list *b)
+{
+    if (ATOM_TYPE(a) != ATOM_TYPE(b))
+        return 0;
+
+    if (IS_TRUE(a) && !IS_TRUE(b))
+        return 0;
+
+    if (IS_FALSE(a) && !IS_FALSE(b))
+        return 0;
+
+    if (IS_TRUE(b) && !IS_TRUE(a))
+        return 0;
+
+    if (IS_FALSE(b) && !IS_FALSE(a))
+        return 0;
+
+    if (IS_NIL(a) && !IS_NIL(b))
+        return 0;
+
+    if (IS_NIL(b) && !IS_NIL(a))
+        return 0;
+
+    int result = 1;
+
+    switch (ATOM_TYPE(a))
+    {
+        case ATOM_INT:
+            if (LIST_GET_ATOM(a)->l != LIST_GET_ATOM(b)->l)
+                result = 0;
+            break;
+
+        case ATOM_STR:
+        case ATOM_SYMBOL:
+            if (strcmp(LIST_GET_ATOM(a)->str.str, LIST_GET_ATOM(b)->str.str) != 0)
+                result = 0;
+            break;
+
+        case ATOM_LIST:
+        {
+            struct list *ai = LIST_GET_ATOM(a)->list;
+            struct list *bi = LIST_GET_ATOM(b)->list;
+
+            while (ai && bi)
+            {
+                if (!atom_cmp(ai, bi))
+                {
+                    result = 0;
+                    break;
+                }
+
+                ai = ai->next;
+                bi = bi->next;
+            }
+
+            if (ai != NULL || bi != NULL)
+                result = 0;
+
+            break;
+        }
+    }
+
+    return result;
+}
+
+struct list *eval(struct list *list)
+{
+    if (!IS_LIST(list))
+        return list;
+
+    struct list *l = LIST_GET_ATOM(list)->list;
+
+    if (IS_SYM(l))
+    {
+        const char *sym = LIST_GET_ATOM(l)->str.str;
+
+        if (strcmp(sym, "quote") == 0)
+        {
+            return l->next;
+        }
+        else if (strcmp(sym, "atom") == 0)
+        {
+            if (IS_LIST(l->next))
+            {
+                return list_append(NULL, &false_atom);
+            }
+            else
+            {
+                return list_append(NULL, &true_atom);
+            }
+        }
+        else if (strcmp(sym, "eq") == 0)
+        {
+            struct list *a = l->next;
+            if (!a)
+                return list_append(NULL, &false_atom);
+
+            struct list *b = a->next;
+            if (!b)
+                return list_append(NULL, &false_atom);
+
+            a = eval(a);
+            b = eval(b);
+
+            if (atom_cmp(a, b))
+                return list_append(NULL, &true_atom);
+
+            return list_append(NULL, &false_atom);
+        }
+        else if (strncmp(sym, "+", 1) == 0 ||
+                 strncmp(sym, "-", 1) == 0 ||
+                 strncmp(sym, "/", 1) == 0 ||
+                 strncmp(sym, "*", 1) == 0)
+        {
+            struct list *oper = CAR(l);
+            struct list *a = CDR(oper);
+            struct list *b = CDDR(oper);
+
+            if (!a || !b)
+                return list_append(NULL, &nil_atom);
+
+            a = eval(a);
+            b = eval(b);
+
+            if (!(ATOM_TYPE(a) == ATOM_TYPE(b) && ATOM_TYPE(a) == ATOM_INT))
+                return list_append(NULL, &nil_atom);
+
+            long numa = LIST_GET_ATOM(a)->l;
+            long numb = LIST_GET_ATOM(b)->l;
+            long numr;
+
+            switch (*sym)
+            {
+                case '+':
+                    numr = numa + numb;
+                    break;
+                case '-':
+                    numr = numa - numb;
+                    break;
+                case '/':
+                    numr = numa / numb;
+                    break;
+                case '*':
+                    numr = numa * numb;
+                    break;
+            }
+
+            struct list *result = list_append(NULL, atom_new_int(numr));
+
+            return result;
+        }
+        else if (strncmp(sym, ">", 1) == 0)
+        {
+            struct list *oper = CAR(l);
+            struct list *a = CDR(oper);
+            struct list *b = CDDR(oper);
+
+            if (!a || !b)
+                return list_append(NULL, &nil_atom);
+
+            a = eval(a);
+            b = eval(b);
+
+            if (!(ATOM_TYPE(a) == ATOM_TYPE(b) && ATOM_TYPE(a) == ATOM_INT))
+                return list_append(NULL, &nil_atom);
+
+            long numa = LIST_GET_ATOM(a)->l;
+            long numb = LIST_GET_ATOM(b)->l;
+
+            if (numa > numb)
+                return list_append(NULL, &true_atom);
+            else
+                return list_append(NULL, &false_atom);
+        }
+        else if (strcmp(sym, "if") == 0)
+        {
+            struct list *predicate = CDR(l);
+            struct list *true_case = CDR(predicate);
+            struct list *false_case = CDR(true_case);
+
+            if (!predicate || !true_case || !false_case)
+                return list_append(NULL, &nil_atom);
+
+            predicate = eval(predicate);
+
+            if (IS_TRUE(predicate))
+                return eval(true_case);
+            else
+                return eval(false_case);
+        }
+    }
+    else if (IS_LIST(l))
+    {
+        return eval(l);
+    }
+
+    return list_append(NULL, &nil_atom);
+}
+
+struct list *eval_str(const char *str)
+{
+    struct list *result;
+    int pos = 0;
+
+    result = eval(parse(str, &pos));
+
+    return result;
+}
+
+#ifdef BUILD_TEST
+
+#include "test_util.h"
+
+TEST(eval)
+{
+    struct list *result;
+    int pos;
+
+#define EVAL(EXPR) \
+    pos = 0; \
+    result = eval(parse((EXPR), &pos))
+
+#define ARITHMETIC_TEST(EXPR, RESULT) \
+    EVAL(EXPR); \
+    ASSERT_EQ(ATOM_INT, ATOM_TYPE(result)); \
+    ASSERT_EQ(RESULT, LIST_GET_ATOM(result)->l)
+
+    ARITHMETIC_TEST("(+ 1 2)", 3);
+    ARITHMETIC_TEST("(- 5 10)", -5);
+    ARITHMETIC_TEST("(/ 42 2)", 21);
+    ARITHMETIC_TEST("(* 5 10)", 50);
+    ARITHMETIC_TEST("(* (* 2 (+ 1 1)) 2)", 8);
+
+#undef ARITHMETIC_TEST
+
+#define EQ_TEST(EXPR, RESULT) \
+    EVAL(EXPR); \
+    ASSERT_EQ(result, RESULT)
+
+#define EQ_TEST_T(EXPR) EVAL(EXPR); ASSERT(IS_TRUE(result))
+#define EQ_TEST_F(EXPR) EVAL(EXPR); ASSERT(IS_FALSE(result))
+
+    EQ_TEST_T("(eq 1 1)");
+    EQ_TEST_T("(eq (+ 1 1) 2)");
+    EQ_TEST_T("(eq (quote (1 2 3)) (quote (1 2 3)))");
+
+    EQ_TEST_T("(eq \"eka\" \"eka\"");
+    EQ_TEST_F("(eq \"eka\" eka)");
+    EQ_TEST_F("(eq \"eka\" 100)");
+    EQ_TEST_F("(eq \"eka\" \"toka\"");
+
+    EQ_TEST_T("(eq eka eka)");
+    EQ_TEST_F("(eq eka toka)");
+
+    EQ_TEST_F("(eq 1 2)");
+    EQ_TEST_F("(eq 1 (- 1 1))");
+    EQ_TEST_F("(eq (quote (1)) (quote (1 2 3)))");
+
+    EQ_TEST_T("(eq (quote (1 2)) '(1 2))");
+    EQ_TEST_T("(eq 'bar 'bar)");
+    EQ_TEST_F("(eq 'foo 'bar)");
+    EQ_TEST_T("(eq (quote bar) 'bar)");
+    EQ_TEST_F("(eq (quote foo) 'bar)");
+
+    EQ_TEST_F("(> 1 2)");
+    EQ_TEST_T("(> 2 1)");
+
+#undef EQ_TEST_F
+#undef EQ_TEST_T
+#undef EQ_TEST
+
+    EVAL("(if #t 1 2)");
+    ASSERT_EQ(1, LIST_GET_ATOM(result)->l);
+
+    EVAL("(if #t (+ 1 1) (* 2 2))");
+    ASSERT_EQ(2, LIST_GET_ATOM(result)->l);
+
+    EVAL("(if #f (+ 1 1) (* 2 2))");
+    ASSERT_EQ(4, LIST_GET_ATOM(result)->l);
+
+#undef EVAL
+}
+
+#endif /* BUILD_TEST */
diff --git a/eval.h b/eval.h
new file mode 100644
index 0000000..d22355b
--- /dev/null
+++ b/eval.h
@@ -0,0 +1,7 @@
+#ifndef EVAL_H
+#define EVAL_H
+
+struct list *eval(struct list *list);
+struct list *eval_str(const char *str);
+
+#endif
diff --git a/linenoise.c b/linenoise.c
new file mode 100644
index 0000000..aef5cdd
--- /dev/null
+++ b/linenoise.c
@@ -0,0 +1,1090 @@
+/* linenoise.c -- guerrilla line editing library against the idea that a
+ * line editing lib needs to be 20,000 lines of C code.
+ *
+ * You can find the latest source code at:
+ * 
+ *   http://github.com/antirez/linenoise
+ *
+ * Does a number of crazy assumptions that happen to be true in 99.9999% of
+ * the 2010 UNIX computers around.
+ *
+ * ------------------------------------------------------------------------
+ *
+ * Copyright (c) 2010-2013, Salvatore Sanfilippo <antirez at gmail dot com>
+ * Copyright (c) 2010-2013, Pieter Noordhuis <pcnoordhuis at gmail dot com>
+ *
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ *  *  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *
+ *  *  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * ------------------------------------------------------------------------
+ *
+ * References:
+ * - http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
+ * - http://www.3waylabs.com/nw/WWW/products/wizcon/vt220.html
+ *
+ * Todo list:
+ * - Filter bogus Ctrl+<char> combinations.
+ * - Win32 support
+ *
+ * Bloat:
+ * - History search like Ctrl+r in readline?
+ *
+ * List of escape sequences used by this program, we do everything just
+ * with three sequences. In order to be so cheap we may have some
+ * flickering effect with some slow terminal, but the lesser sequences
+ * the more compatible.
+ *
+ * CHA (Cursor Horizontal Absolute)
+ *    Sequence: ESC [ n G
+ *    Effect: moves cursor to column n
+ *
+ * EL (Erase Line)
+ *    Sequence: ESC [ n K
+ *    Effect: if n is 0 or missing, clear from cursor to end of line
+ *    Effect: if n is 1, clear from beginning of line to cursor
+ *    Effect: if n is 2, clear entire line
+ *
+ * CUF (CUrsor Forward)
+ *    Sequence: ESC [ n C
+ *    Effect: moves cursor forward of n chars
+ *
+ * When multi line mode is enabled, we also use an additional escape
+ * sequence. However multi line editing is disabled by default.
+ *
+ * CUU (Cursor Up)
+ *    Sequence: ESC [ n A
+ *    Effect: moves cursor up of n chars.
+ *
+ * CUD (Cursor Down)
+ *    Sequence: ESC [ n B
+ *    Effect: moves cursor down of n chars.
+ *
+ * The following are used to clear the screen: ESC [ H ESC [ 2 J
+ * This is actually composed of two sequences:
+ *
+ * cursorhome
+ *    Sequence: ESC [ H
+ *    Effect: moves the cursor to upper left corner
+ *
+ * ED2 (Clear entire screen)
+ *    Sequence: ESC [ 2 J
+ *    Effect: clear the whole screen
+ * 
+ */
+
+#include <termios.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <stdlib.h>
+#include <ctype.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include "linenoise.h"
+
+#define LINENOISE_DEFAULT_HISTORY_MAX_LEN 100
+#define LINENOISE_MAX_LINE 4096
+static char *unsupported_term[] = {"dumb","cons25","emacs",NULL};
+static linenoiseCompletionCallback *completionCallback = NULL;
+
+static struct termios orig_termios; /* In order to restore at exit.*/
+static int rawmode = 0; /* For atexit() function to check if restore is needed*/
+static int mlmode = 0;  /* Multi line mode. Default is single line. */
+static int atexit_registered = 0; /* Register atexit just 1 time. */
+static int history_max_len = LINENOISE_DEFAULT_HISTORY_MAX_LEN;
+static int history_len = 0;
+static char **history = NULL;
+
+/* The linenoiseState structure represents the state during line editing.
+ * We pass this state to functions implementing specific editing
+ * functionalities. */
+struct linenoiseState {
+    int ifd;            /* Terminal stdin file descriptor. */
+    int ofd;            /* Terminal stdout file descriptor. */
+    char *buf;          /* Edited line buffer. */
+    size_t buflen;      /* Edited line buffer size. */
+    const char *prompt; /* Prompt to display. */
+    size_t plen;        /* Prompt length. */
+    size_t pos;         /* Current cursor position. */
+    size_t oldpos;      /* Previous refresh cursor position. */
+    size_t len;         /* Current edited line length. */
+    size_t cols;        /* Number of columns in terminal. */
+    size_t maxrows;     /* Maximum num of rows used so far (multiline mode) */
+    int history_index;  /* The history index we are currently editing. */
+};
+
+enum KEY_ACTION{
+	KEY_NULL = 0,	    /* NULL */
+	CTRL_A = 1,         /* Ctrl+a */
+	CTRL_B = 2,         /* Ctrl-b */
+	CTRL_C = 3,         /* Ctrl-c */
+	CTRL_D = 4,         /* Ctrl-d */
+	CTRL_E = 5,         /* Ctrl-e */
+	CTRL_F = 6,         /* Ctrl-f */
+	CTRL_H = 8,         /* Ctrl-h */
+	TAB = 9,            /* Tab */
+	CTRL_K = 11,        /* Ctrl+k */
+	CTRL_L = 12,        /* Ctrl+l */
+	ENTER = 13,         /* Enter */
+	CTRL_N = 14,        /* Ctrl-n */
+	CTRL_P = 16,        /* Ctrl-p */
+	CTRL_T = 20,        /* Ctrl-t */
+	CTRL_U = 21,        /* Ctrl+u */
+	CTRL_W = 23,        /* Ctrl+w */
+	ESC = 27,           /* Escape */
+	BACKSPACE =  127    /* Backspace */
+};
+
+static void linenoiseAtExit(void);
+int linenoiseHistoryAdd(const char *line);
+static void refreshLine(struct linenoiseState *l);
+
+/* Debugging macro. */
+#if 0
+FILE *lndebug_fp = NULL;
+#define lndebug(...) \
+    do { \
+        if (lndebug_fp == NULL) { \
+            lndebug_fp = fopen("/tmp/lndebug.txt","a"); \
+            fprintf(lndebug_fp, \
+            "[%d %d %d] p: %d, rows: %d, rpos: %d, max: %d, oldmax: %d\n", \
+            (int)l->len,(int)l->pos,(int)l->oldpos,plen,rows,rpos, \
+            (int)l->maxrows,old_rows); \
+        } \
+        fprintf(lndebug_fp, ", " __VA_ARGS__); \
+        fflush(lndebug_fp); \
+    } while (0)
+#else
+#define lndebug(fmt, ...)
+#endif
+
+/* ======================= Low level terminal handling ====================== */
+
+/* Set if to use or not the multi line mode. */
+void linenoiseSetMultiLine(int ml) {
+    mlmode = ml;
+}
+
+/* Return true if the terminal name is in the list of terminals we know are
+ * not able to understand basic escape sequences. */
+static int isUnsupportedTerm(void) {
+    char *term = getenv("TERM");
+    int j;
+
+    if (term == NULL) return 0;
+    for (j = 0; unsupported_term[j]; j++)
+        if (!strcasecmp(term,unsupported_term[j])) return 1;
+    return 0;
+}
+
+/* Raw mode: 1960 magic shit. */
+static int enableRawMode(int fd) {
+    struct termios raw;
+
+    if (!isatty(STDIN_FILENO)) goto fatal;
+    if (!atexit_registered) {
+        atexit(linenoiseAtExit);
+        atexit_registered = 1;
+    }
+    if (tcgetattr(fd,&orig_termios) == -1) goto fatal;
+
+    raw = orig_termios;  /* modify the original mode */
+    /* input modes: no break, no CR to NL, no parity check, no strip char,
+     * no start/stop output control. */
+    raw.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
+    /* output modes - disable post processing */
+    raw.c_oflag &= ~(OPOST);
+    /* control modes - set 8 bit chars */
+    raw.c_cflag |= (CS8);
+    /* local modes - choing off, canonical off, no extended functions,
+     * no signal chars (^Z,^C) */
+    raw.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
+    /* control chars - set return condition: min number of bytes and timer.
+     * We want read to return every single byte, without timeout. */
+    raw.c_cc[VMIN] = 1; raw.c_cc[VTIME] = 0; /* 1 byte, no timer */
+
+    /* put terminal in raw mode after flushing */
+    if (tcsetattr(fd,TCSAFLUSH,&raw) < 0) goto fatal;
+    rawmode = 1;
+    return 0;
+
+fatal:
+    errno = ENOTTY;
+    return -1;
+}
+
+static void disableRawMode(int fd) {
+    /* Don't even check the return value as it's too late. */
+    if (rawmode && tcsetattr(fd,TCSAFLUSH,&orig_termios) != -1)
+        rawmode = 0;
+}
+
+/* Use the ESC [6n escape sequence to query the horizontal cursor position
+ * and return it. On error -1 is returned, on success the position of the
+ * cursor. */
+static int getCursorPosition(int ifd, int ofd) {
+    char buf[32];
+    int cols, rows;
+    unsigned int i = 0;
+
+    /* Report cursor location */
+    if (write(ofd, "\x1b[6n", 4) != 4) return -1;
+
+    /* Read the response: ESC [ rows ; cols R */
+    while (i < sizeof(buf)-1) {
+        if (read(ifd,buf+i,1) != 1) break;
+        if (buf[i] == 'R') break;
+        i++;
+    }
+    buf[i] = '\0';
+
+    /* Parse it. */
+    if (buf[0] != ESC || buf[1] != '[') return -1;
+    if (sscanf(buf+2,"%d;%d",&rows,&cols) != 2) return -1;
+    return cols;
+}
+
+/* Try to get the number of columns in the current terminal, or assume 80
+ * if it fails. */
+static int getColumns(int ifd, int ofd) {
+    struct winsize ws;
+
+    if (ioctl(1, TIOCGWINSZ, &ws) == -1 || ws.ws_col == 0) {
+        /* ioctl() failed. Try to query the terminal itself. */
+        int start, cols;
+
+        /* Get the initial position so we can restore it later. */
+        start = getCursorPosition(ifd,ofd);
+        if (start == -1) goto failed;
+
+        /* Go to right margin and get position. */
+        if (write(ofd,"\x1b[999C",6) != 6) goto failed;
+        cols = getCursorPosition(ifd,ofd);
+        if (cols == -1) goto failed;
+
+        /* Restore position. */
+        if (cols > start) {
+            char seq[32];
+            snprintf(seq,32,"\x1b[%dD",cols-start);
+            if (write(ofd,seq,strlen(seq)) == -1) {
+                /* Can't recover... */
+            }
+        }
+        return cols;
+    } else {
+        return ws.ws_col;
+    }
+
+failed:
+    return 80;
+}
+
+/* Clear the screen. Used to handle ctrl+l */
+void linenoiseClearScreen(void) {
+    if (write(STDOUT_FILENO,"\x1b[H\x1b[2J",7) <= 0) {
+        /* nothing to do, just to avoid warning. */
+    }
+}
+
+/* Beep, used for completion when there is nothing to complete or when all
+ * the choices were already shown. */
+static void linenoiseBeep(void) {
+    fprintf(stderr, "\x7");
+    fflush(stderr);
+}
+
+/* ============================== Completion ================================ */
+
+/* Free a list of completion option populated by linenoiseAddCompletion(). */
+static void freeCompletions(linenoiseCompletions *lc) {
+    size_t i;
+    for (i = 0; i < lc->len; i++)
+        free(lc->cvec[i]);
+    if (lc->cvec != NULL)
+        free(lc->cvec);
+}
+
+/* This is an helper function for linenoiseEdit() and is called when the
+ * user types the <tab> key in order to complete the string currently in the
+ * input.
+ * 
+ * The state of the editing is encapsulated into the pointed linenoiseState
+ * structure as described in the structure definition. */
+static int completeLine(struct linenoiseState *ls) {
+    linenoiseCompletions lc = { 0, NULL };
+    int nread, nwritten;
+    char c = 0;
+
+    completionCallback(ls->buf,&lc);
+    if (lc.len == 0) {
+        linenoiseBeep();
+    } else {
+        size_t stop = 0, i = 0;
+
+        while(!stop) {
+            /* Show completion or original buffer */
+            if (i < lc.len) {
+                struct linenoiseState saved = *ls;
+
+                ls->len = ls->pos = strlen(lc.cvec[i]);
+                ls->buf = lc.cvec[i];
+                refreshLine(ls);
+                ls->len = saved.len;
+                ls->pos = saved.pos;
+                ls->buf = saved.buf;
+            } else {
+                refreshLine(ls);
+            }
+
+            nread = read(ls->ifd,&c,1);
+            if (nread <= 0) {
+                freeCompletions(&lc);
+                return -1;
+            }
+
+            switch(c) {
+                case 9: /* tab */
+                    i = (i+1) % (lc.len+1);
+                    if (i == lc.len) linenoiseBeep();
+                    break;
+                case 27: /* escape */
+                    /* Re-show original buffer */
+                    if (i < lc.len) refreshLine(ls);
+                    stop = 1;
+                    break;
+                default:
+                    /* Update buffer and return */
+                    if (i < lc.len) {
+                        nwritten = snprintf(ls->buf,ls->buflen,"%s",lc.cvec[i]);
+                        ls->len = ls->pos = nwritten;
+                    }
+                    stop = 1;
+                    break;
+            }
+        }
+    }
+
+    freeCompletions(&lc);
+    return c; /* Return last read character */
+}
+
+/* Register a callback function to be called for tab-completion. */
+void linenoiseSetCompletionCallback(linenoiseCompletionCallback *fn) {
+    completionCallback = fn;
+}
+
+/* This function is used by the callback function registered by the user
+ * in order to add completion options given the input string when the
+ * user typed <tab>. See the example.c source code for a very easy to
+ * understand example. */
+void linenoiseAddCompletion(linenoiseCompletions *lc, const char *str) {
+    size_t len = strlen(str);
+    char *copy, **cvec;
+
+    copy = malloc(len+1);
+    if (copy == NULL) return;
+    memcpy(copy,str,len+1);
+    cvec = realloc(lc->cvec,sizeof(char*)*(lc->len+1));
+    if (cvec == NULL) {
+        free(copy);
+        return;
+    }
+    lc->cvec = cvec;
+    lc->cvec[lc->len++] = copy;
+}
+
+/* =========================== Line editing ================================= */
+
+/* We define a very simple "append buffer" structure, that is an heap
+ * allocated string where we can append to. This is useful in order to
+ * write all the escape sequences in a buffer and flush them to the standard
+ * output in a single call, to avoid flickering effects. */
+struct abuf {
+    char *b;
+    int len;
+};
+
+static void abInit(struct abuf *ab) {
+    ab->b = NULL;
+    ab->len = 0;
+}
+
+static void abAppend(struct abuf *ab, const char *s, int len) {
+    char *new = realloc(ab->b,ab->len+len);
+
+    if (new == NULL) return;
+    memcpy(new+ab->len,s,len);
+    ab->b = new;
+    ab->len += len;
+}
+
+static void abFree(struct abuf *ab) {
+    free(ab->b);
+}
+
+/* Single line low level line refresh.
+ *
+ * Rewrite the currently edited line accordingly to the buffer content,
+ * cursor position, and number of columns of the terminal. */
+static void refreshSingleLine(struct linenoiseState *l) {
+    char seq[64];
+    size_t plen = strlen(l->prompt);
+    int fd = l->ofd;
+    char *buf = l->buf;
+    size_t len = l->len;
+    size_t pos = l->pos;
+    struct abuf ab;
+    
+    while((plen+pos) >= l->cols) {
+        buf++;
+        len--;
+        pos--;
+    }
+    while (plen+len > l->cols) {
+        len--;
+    }
+
+    abInit(&ab);
+    /* Cursor to left edge */
+    snprintf(seq,64,"\x1b[0G");
+    abAppend(&ab,seq,strlen(seq));
+    /* Write the prompt and the current buffer content */
+    abAppend(&ab,l->prompt,strlen(l->prompt));
+    abAppend(&ab,buf,len);
+    /* Erase to right */
+    snprintf(seq,64,"\x1b[0K");
+    abAppend(&ab,seq,strlen(seq));
+    /* Move cursor to original position. */
+    snprintf(seq,64,"\x1b[0G\x1b[%dC", (int)(pos+plen));
+    abAppend(&ab,seq,strlen(seq));
+    if (write(fd,ab.b,ab.len) == -1) {} /* Can't recover from write error. */
+    abFree(&ab);
+}
+
+/* Multi line low level line refresh.
+ *
+ * Rewrite the currently edited line accordingly to the buffer content,
+ * cursor position, and number of columns of the terminal. */
+static void refreshMultiLine(struct linenoiseState *l) {
+    char seq[64];
+    int plen = strlen(l->prompt);
+    int rows = (plen+l->len+l->cols-1)/l->cols; /* rows used by current buf. */
+    int rpos = (plen+l->oldpos+l->cols)/l->cols; /* cursor relative row. */
+    int rpos2; /* rpos after refresh. */
+    int old_rows = l->maxrows;
+    int fd = l->ofd, j;
+    struct abuf ab;
+
+    /* Update maxrows if needed. */
+    if (rows > (int)l->maxrows) l->maxrows = rows;
+
+    /* First step: clear all the lines used before. To do so start by
+     * going to the last row. */
+    abInit(&ab);
+    if (old_rows-rpos > 0) {
+        lndebug("go down %d", old_rows-rpos);
+        snprintf(seq,64,"\x1b[%dB", old_rows-rpos);
+        abAppend(&ab,seq,strlen(seq));
+    }
+
+    /* Now for every row clear it, go up. */
+    for (j = 0; j < old_rows-1; j++) {
+        lndebug("clear+up");
+        snprintf(seq,64,"\x1b[0G\x1b[0K\x1b[1A");
+        abAppend(&ab,seq,strlen(seq));
+    }
+
+    /* Clean the top line. */
+    lndebug("clear");
+    snprintf(seq,64,"\x1b[0G\x1b[0K");
+    abAppend(&ab,seq,strlen(seq));
+    
+    /* Write the prompt and the current buffer content */
+    abAppend(&ab,l->prompt,strlen(l->prompt));
+    abAppend(&ab,l->buf,l->len);
+
+    /* If we are at the very end of the screen with our prompt, we need to
+     * emit a newline and move the prompt to the first column. */
+    if (l->pos &&
+        l->pos == l->len &&
+        (l->pos+plen) % l->cols == 0)
+    {
+        lndebug("<newline>");
+        abAppend(&ab,"\n",1);
+        snprintf(seq,64,"\x1b[0G");
+        abAppend(&ab,seq,strlen(seq));
+        rows++;
+        if (rows > (int)l->maxrows) l->maxrows = rows;
+    }
+
+    /* Move cursor to right position. */
+    rpos2 = (plen+l->pos+l->cols)/l->cols; /* current cursor relative row. */
+    lndebug("rpos2 %d", rpos2);
+
+    /* Go up till we reach the expected positon. */
+    if (rows-rpos2 > 0) {
+        lndebug("go-up %d", rows-rpos2);
+        snprintf(seq,64,"\x1b[%dA", rows-rpos2);
+        abAppend(&ab,seq,strlen(seq));
+    }
+
+    /* Set column. */
+    lndebug("set col %d", 1+((plen+(int)l->pos) % (int)l->cols));
+    snprintf(seq,64,"\x1b[%dG", 1+((plen+(int)l->pos) % (int)l->cols));
+    abAppend(&ab,seq,strlen(seq));
+
+    lndebug("\n");
+    l->oldpos = l->pos;
+
+    if (write(fd,ab.b,ab.len) == -1) {} /* Can't recover from write error. */
+    abFree(&ab);
+}
+
+/* Calls the two low level functions refreshSingleLine() or
+ * refreshMultiLine() according to the selected mode. */
+static void refreshLine(struct linenoiseState *l) {
+    if (mlmode)
+        refreshMultiLine(l);
+    else
+        refreshSingleLine(l);
+}
+
+/* Insert the character 'c' at cursor current position.
+ *
+ * On error writing to the terminal -1 is returned, otherwise 0. */
+int linenoiseEditInsert(struct linenoiseState *l, char c) {
+    if (l->len < l->buflen) {
+        if (l->len == l->pos) {
+            l->buf[l->pos] = c;
+            l->pos++;
+            l->len++;
+            l->buf[l->len] = '\0';
+            if ((!mlmode && l->plen+l->len < l->cols) /* || mlmode */) {
+                /* Avoid a full update of the line in the
+                 * trivial case. */
+                if (write(l->ofd,&c,1) == -1) return -1;
+            } else {
+                refreshLine(l);
+            }
+        } else {
+            memmove(l->buf+l->pos+1,l->buf+l->pos,l->len-l->pos);
+            l->buf[l->pos] = c;
+            l->len++;
+            l->pos++;
+            l->buf[l->len] = '\0';
+            refreshLine(l);
+        }
+    }
+    return 0;
+}
+
+/* Move cursor on the left. */
+void linenoiseEditMoveLeft(struct linenoiseState *l) {
+    if (l->pos > 0) {
+        l->pos--;
+        refreshLine(l);
+    }
+}
+
+/* Move cursor on the right. */
+void linenoiseEditMoveRight(struct linenoiseState *l) {
+    if (l->pos != l->len) {
+        l->pos++;
+        refreshLine(l);
+    }
+}
+
+/* Move cursor to the start of the line. */
+void linenoiseEditMoveHome(struct linenoiseState *l) {
+    if (l->pos != 0) {
+        l->pos = 0;
+        refreshLine(l);
+    }
+}
+
+/* Move cursor to the end of the line. */
+void linenoiseEditMoveEnd(struct linenoiseState *l) {
+    if (l->pos != l->len) {
+        l->pos = l->len;
+        refreshLine(l);
+    }
+}
+
+/* Substitute the currently edited line with the next or previous history
+ * entry as specified by 'dir'. */
+#define LINENOISE_HISTORY_NEXT 0
+#define LINENOISE_HISTORY_PREV 1
+void linenoiseEditHistoryNext(struct linenoiseState *l, int dir) {
+    if (history_len > 1) {
+        /* Update the current history entry before to
+         * overwrite it with the next one. */
+        free(history[history_len - 1 - l->history_index]);
+        history[history_len - 1 - l->history_index] = strdup(l->buf);
+        /* Show the new entry */
+        l->history_index += (dir == LINENOISE_HISTORY_PREV) ? 1 : -1;
+        if (l->history_index < 0) {
+            l->history_index = 0;
+            return;
+        } else if (l->history_index >= history_len) {
+            l->history_index = history_len-1;
+            return;
+        }
+        strncpy(l->buf,history[history_len - 1 - l->history_index],l->buflen);
+        l->buf[l->buflen-1] = '\0';
+        l->len = l->pos = strlen(l->buf);
+        refreshLine(l);
+    }
+}
+
+/* Delete the character at the right of the cursor without altering the cursor
+ * position. Basically this is what happens with the "Delete" keyboard key. */
+void linenoiseEditDelete(struct linenoiseState *l) {
+    if (l->len > 0 && l->pos < l->len) {
+        memmove(l->buf+l->pos,l->buf+l->pos+1,l->len-l->pos-1);
+        l->len--;
+        l->buf[l->len] = '\0';
+        refreshLine(l);
+    }
+}
+
+/* Backspace implementation. */
+void linenoiseEditBackspace(struct linenoiseState *l) {
+    if (l->pos > 0 && l->len > 0) {
+        memmove(l->buf+l->pos-1,l->buf+l->pos,l->len-l->pos);
+        l->pos--;
+        l->len--;
+        l->buf[l->len] = '\0';
+        refreshLine(l);
+    }
+}
+
+/* Delete the previosu word, maintaining the cursor at the start of the
+ * current word. */
+void linenoiseEditDeletePrevWord(struct linenoiseState *l) {
+    size_t old_pos = l->pos;
+    size_t diff;
+
+    while (l->pos > 0 && l->buf[l->pos-1] == ' ')
+        l->pos--;
+    while (l->pos > 0 && l->buf[l->pos-1] != ' ')
+        l->pos--;
+    diff = old_pos - l->pos;
+    memmove(l->buf+l->pos,l->buf+old_pos,l->len-old_pos+1);
+    l->len -= diff;
+    refreshLine(l);
+}
+
+/* This function is the core of the line editing capability of linenoise.
+ * It expects 'fd' to be already in "raw mode" so that every key pressed
+ * will be returned ASAP to read().
+ *
+ * The resulting string is put into 'buf' when the user type enter, or
+ * when ctrl+d is typed.
+ *
+ * The function returns the length of the current buffer. */
+static int linenoiseEdit(int stdin_fd, int stdout_fd, char *buf, size_t buflen, const char *prompt)
+{
+    struct linenoiseState l;
+
+    /* Populate the linenoise state that we pass to functions implementing
+     * specific editing functionalities. */
+    l.ifd = stdin_fd;
+    l.ofd = stdout_fd;
+    l.buf = buf;
+    l.buflen = buflen;
+    l.prompt = prompt;
+    l.plen = strlen(prompt);
+    l.oldpos = l.pos = 0;
+    l.len = 0;
+    l.cols = getColumns(stdin_fd, stdout_fd);
+    l.maxrows = 0;
+    l.history_index = 0;
+
+    /* Buffer starts empty. */
+    l.buf[0] = '\0';
+    l.buflen--; /* Make sure there is always space for the nulterm */
+
+    /* The latest history entry is always our current buffer, that
+     * initially is just an empty string. */
+    linenoiseHistoryAdd("");
+    
+    if (write(l.ofd,prompt,l.plen) == -1) return -1;
+    while(1) {
+        char c;
+        int nread;
+        char seq[3];
+
+        nread = read(l.ifd,&c,1);
+        if (nread <= 0) return l.len;
+
+        /* Only autocomplete when the callback is set. It returns < 0 when
+         * there was an error reading from fd. Otherwise it will return the
+         * character that should be handled next. */
+        if (c == 9 && completionCallback != NULL) {
+            c = completeLine(&l);
+            /* Return on errors */
+            if (c < 0) return l.len;
+            /* Read next character when 0 */
+            if (c == 0) continue;
+        }
+
+        switch(c) {
+        case ENTER:    /* enter */
+            history_len--;
+            free(history[history_len]);
+            return (int)l.len;
+        case CTRL_C:     /* ctrl-c */
+            errno = EAGAIN;
+            return -1;
+        case BACKSPACE:   /* backspace */
+        case 8:     /* ctrl-h */
+            linenoiseEditBackspace(&l);
+            break;
+        case CTRL_D:     /* ctrl-d, remove char at right of cursor, or of the
+                       line is empty, act as end-of-file. */
+            if (l.len > 0) {
+                linenoiseEditDelete(&l);
+            } else {
+                history_len--;
+                free(history[history_len]);
+                return -1;
+            }
+            break;
+        case CTRL_T:    /* ctrl-t, swaps current character with previous. */
+            if (l.pos > 0 && l.pos < l.len) {
+                int aux = buf[l.pos-1];
+                buf[l.pos-1] = buf[l.pos];
+                buf[l.pos] = aux;
+                if (l.pos != l.len-1) l.pos++;
+                refreshLine(&l);
+            }
+            break;
+        case CTRL_B:     /* ctrl-b */
+            linenoiseEditMoveLeft(&l);
+            break;
+        case CTRL_F:     /* ctrl-f */
+            linenoiseEditMoveRight(&l);
+            break;
+        case CTRL_P:    /* ctrl-p */
+            linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_PREV);
+            break;
+        case CTRL_N:    /* ctrl-n */
+            linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_NEXT);
+            break;
+        case ESC:    /* escape sequence */
+            /* Read the next two bytes representing the escape sequence.
+             * Use two calls to handle slow terminals returning the two
+             * chars at different times. */
+            if (read(l.ifd,seq,1) == -1) break;
+            if (read(l.ifd,seq+1,1) == -1) break;
+
+            /* ESC [ sequences. */
+            if (seq[0] == '[') {
+                if (seq[1] >= '0' && seq[1] <= '9') {
+                    /* Extended escape, read additional byte. */
+                    if (read(l.ifd,seq+2,1) == -1) break;
+                    if (seq[2] == '~') {
+                        switch(seq[1]) {
+                        case '3': /* Delete key. */
+                            linenoiseEditDelete(&l);
+                            break;
+                        }
+                    }
+                } else {
+                    switch(seq[1]) {
+                    case 'A': /* Up */
+                        linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_PREV);
+                        break;
+                    case 'B': /* Down */
+                        linenoiseEditHistoryNext(&l, LINENOISE_HISTORY_NEXT);
+                        break;
+                    case 'C': /* Right */
+                        linenoiseEditMoveRight(&l);
+                        break;
+                    case 'D': /* Left */
+                        linenoiseEditMoveLeft(&l);
+                        break;
+                    case 'H': /* Home */
+                        linenoiseEditMoveHome(&l);
+                        break;
+                    case 'F': /* End*/
+                        linenoiseEditMoveEnd(&l);
+                        break;
+                    }
+                }
+            }
+
+            /* ESC O sequences. */
+            else if (seq[0] == 'O') {
+                switch(seq[1]) {
+                case 'H': /* Home */
+                    linenoiseEditMoveHome(&l);
+                    break;
+                case 'F': /* End*/
+                    linenoiseEditMoveEnd(&l);
+                    break;
+                }
+            }
+            break;
+        default:
+            if (linenoiseEditInsert(&l,c)) return -1;
+            break;
+        case CTRL_U: /* Ctrl+u, delete the whole line. */
+            buf[0] = '\0';
+            l.pos = l.len = 0;
+            refreshLine(&l);
+            break;
+        case CTRL_K: /* Ctrl+k, delete from current to end of line. */
+            buf[l.pos] = '\0';
+            l.len = l.pos;
+            refreshLine(&l);
+            break;
+        case CTRL_A: /* Ctrl+a, go to the start of the line */
+            linenoiseEditMoveHome(&l);
+            break;
+        case CTRL_E: /* ctrl+e, go to the end of the line */
+            linenoiseEditMoveEnd(&l);
+            break;
+        case CTRL_L: /* ctrl+l, clear screen */
+            linenoiseClearScreen();
+            refreshLine(&l);
+            break;
+        case CTRL_W: /* ctrl+w, delete previous word */
+            linenoiseEditDeletePrevWord(&l);
+            break;
+        }
+    }
+    return l.len;
+}
+
+/* This special mode is used by linenoise in order to print scan codes
+ * on screen for debugging / development purposes. It is implemented
+ * by the linenoise_example program using the --keycodes option. */
+void linenoisePrintKeyCodes(void) {
+    char quit[4];
+
+    printf("Linenoise key codes debugging mode.\n"
+            "Press keys to see scan codes. Type 'quit' at any time to exit.\n");
+    if (enableRawMode(STDIN_FILENO) == -1) return;
+    memset(quit,' ',4);
+    while(1) {
+        char c;
+        int nread;
+
+        nread = read(STDIN_FILENO,&c,1);
+        if (nread <= 0) continue;
+        memmove(quit,quit+1,sizeof(quit)-1); /* shift string to left. */
+        quit[sizeof(quit)-1] = c; /* Insert current char on the right. */
+        if (memcmp(quit,"quit",sizeof(quit)) == 0) break;
+
+        printf("'%c' %02x (%d) (type quit to exit)\n",
+            isprint(c) ? c : '?', (int)c, (int)c);
+        printf("\x1b[0G"); /* Go left edge manually, we are in raw mode. */
+        fflush(stdout);
+    }
+    disableRawMode(STDIN_FILENO);
+}
+
+/* This function calls the line editing function linenoiseEdit() using
+ * the STDIN file descriptor set in raw mode. */
+static int linenoiseRaw(char *buf, size_t buflen, const char *prompt) {
+    int count;
+
+    if (buflen == 0) {
+        errno = EINVAL;
+        return -1;
+    }
+    if (!isatty(STDIN_FILENO)) {
+        /* Not a tty: read from file / pipe. */
+        if (fgets(buf, buflen, stdin) == NULL) return -1;
+        count = strlen(buf);
+        if (count && buf[count-1] == '\n') {
+            count--;
+            buf[count] = '\0';
+        }
+    } else {
+        /* Interactive editing. */
+        if (enableRawMode(STDIN_FILENO) == -1) return -1;
+        count = linenoiseEdit(STDIN_FILENO, STDOUT_FILENO, buf, buflen, prompt);
+        disableRawMode(STDIN_FILENO);
+        printf("\n");
+    }
+    return count;
+}
+
+/* The high level function that is the main API of the linenoise library.
+ * This function checks if the terminal has basic capabilities, just checking
+ * for a blacklist of stupid terminals, and later either calls the line
+ * editing function or uses dummy fgets() so that you will be able to type
+ * something even in the most desperate of the conditions. */
+char *linenoise(const char *prompt) {
+    char buf[LINENOISE_MAX_LINE];
+    int count;
+
+    if (isUnsupportedTerm()) {
+        size_t len;
+
+        printf("%s",prompt);
+        fflush(stdout);
+        if (fgets(buf,LINENOISE_MAX_LINE,stdin) == NULL) return NULL;
+        len = strlen(buf);
+        while(len && (buf[len-1] == '\n' || buf[len-1] == '\r')) {
+            len--;
+            buf[len] = '\0';
+        }
+        return strdup(buf);
+    } else {
+        count = linenoiseRaw(buf,LINENOISE_MAX_LINE,prompt);
+        if (count == -1) return NULL;
+        return strdup(buf);
+    }
+}
+
+/* ================================ History ================================= */
+
+/* Free the history, but does not reset it. Only used when we have to
+ * exit() to avoid memory leaks are reported by valgrind & co. */
+static void freeHistory(void) {
+    if (history) {
+        int j;
+
+        for (j = 0; j < history_len; j++)
+            free(history[j]);
+        free(history);
+    }
+}
+
+/* At exit we'll try to fix the terminal to the initial conditions. */
+static void linenoiseAtExit(void) {
+    disableRawMode(STDIN_FILENO);
+    freeHistory();
+}
+
+/* This is the API call to add a new entry in the linenoise history.
+ * It uses a fixed array of char pointers that are shifted (memmoved)
+ * when the history max length is reached in order to remove the older
+ * entry and make room for the new one, so it is not exactly suitable for huge
+ * histories, but will work well for a few hundred of entries.
+ *
+ * Using a circular buffer is smarter, but a bit more complex to handle. */
+int linenoiseHistoryAdd(const char *line) {
+    char *linecopy;
+
+    if (history_max_len == 0) return 0;
+
+    /* Initialization on first call. */
+    if (history == NULL) {
+        history = malloc(sizeof(char*)*history_max_len);
+        if (history == NULL) return 0;
+        memset(history,0,(sizeof(char*)*history_max_len));
+    }
+
+    /* Don't add duplicated lines. */
+    if (history_len && !strcmp(history[history_len-1], line)) return 0;
+
+    /* Add an heap allocated copy of the line in the history.
+     * If we reached the max length, remove the older line. */
+    linecopy = strdup(line);
+    if (!linecopy) return 0;
+    if (history_len == history_max_len) {
+        free(history[0]);
+        memmove(history,history+1,sizeof(char*)*(history_max_len-1));
+        history_len--;
+    }
+    history[history_len] = linecopy;
+    history_len++;
+    return 1;
+}
+
+/* Set the maximum length for the history. This function can be called even
+ * if there is already some history, the function will make sure to retain
+ * just the latest 'len' elements if the new history length value is smaller
+ * than the amount of items already inside the history. */
+int linenoiseHistorySetMaxLen(int len) {
+    char **new;
+
+    if (len < 1) return 0;
+    if (history) {
+        int tocopy = history_len;
+
+        new = malloc(sizeof(char*)*len);
+        if (new == NULL) return 0;
+
+        /* If we can't copy everything, free the elements we'll not use. */
+        if (len < tocopy) {
+            int j;
+
+            for (j = 0; j < tocopy-len; j++) free(history[j]);
+            tocopy = len;
+        }
+        memset(new,0,sizeof(char*)*len);
+        memcpy(new,history+(history_len-tocopy), sizeof(char*)*tocopy);
+        free(history);
+        history = new;
+    }
+    history_max_len = len;
+    if (history_len > history_max_len)
+        history_len = history_max_len;
+    return 1;
+}
+
+/* Save the history in the specified file. On success 0 is returned
+ * otherwise -1 is returned. */
+int linenoiseHistorySave(const char *filename) {
+    FILE *fp = fopen(filename,"w");
+    int j;
+    
+    if (fp == NULL) return -1;
+    for (j = 0; j < history_len; j++)
+        fprintf(fp,"%s\n",history[j]);
+    fclose(fp);
+    return 0;
+}
+
+/* Load the history from the specified file. If the file does not exist
+ * zero is returned and no operation is performed.
+ *
+ * If the file exists and the operation succeeded 0 is returned, otherwise
+ * on error -1 is returned. */
+int linenoiseHistoryLoad(const char *filename) {
+    FILE *fp = fopen(filename,"r");
+    char buf[LINENOISE_MAX_LINE];
+    
+    if (fp == NULL) return -1;
+
+    while (fgets(buf,LINENOISE_MAX_LINE,fp) != NULL) {
+        char *p;
+        
+        p = strchr(buf,'\r');
+        if (!p) p = strchr(buf,'\n');
+        if (p) *p = '\0';
+        linenoiseHistoryAdd(buf);
+    }
+    fclose(fp);
+    return 0;
+}
diff --git a/linenoise.h b/linenoise.h
new file mode 100644
index 0000000..e22ebd3
--- /dev/null
+++ b/linenoise.h
@@ -0,0 +1,66 @@
+/* linenoise.h -- guerrilla line editing library against the idea that a
+ * line editing lib needs to be 20,000 lines of C code.
+ *
+ * See linenoise.c for more information.
+ *
+ * ------------------------------------------------------------------------
+ *
+ * Copyright (c) 2010, Salvatore Sanfilippo <antirez at gmail dot com>
+ * Copyright (c) 2010, Pieter Noordhuis <pcnoordhuis at gmail dot com>
+ *
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ * 
+ *  *  Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *
+ *  *  Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __LINENOISE_H
+#define __LINENOISE_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct linenoiseCompletions {
+  size_t len;
+  char **cvec;
+} linenoiseCompletions;
+
+typedef void(linenoiseCompletionCallback)(const char *, linenoiseCompletions *);
+void linenoiseSetCompletionCallback(linenoiseCompletionCallback *);
+void linenoiseAddCompletion(linenoiseCompletions *, const char *);
+
+char *linenoise(const char *prompt);
+int linenoiseHistoryAdd(const char *line);
+int linenoiseHistorySetMaxLen(int len);
+int linenoiseHistorySave(const char *filename);
+int linenoiseHistoryLoad(const char *filename);
+void linenoiseClearScreen(void);
+void linenoiseSetMultiLine(int ml);
+void linenoisePrintKeyCodes(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __LINENOISE_H */
diff --git a/list.c b/list.c
new file mode 100644
index 0000000..58510ac
--- /dev/null
+++ b/list.c
@@ -0,0 +1,99 @@
+#include "list.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+void list_init(struct list *list)
+{
+    memset(list, 0, sizeof(*list));
+}
+
+struct list *list_new(void *data)
+{
+    struct list *list = calloc(1, sizeof(*list));
+    list->data = data;
+    return list;
+}
+
+struct list *list_append(struct list *list, void *data)
+{
+    if (list == NULL)
+    {
+        return list_new(data);
+    }
+
+    struct list *last = list_get_last(list);
+    list = list_new(data);
+    last->next = list;
+
+    return list;
+}
+
+struct list *list_get_last(struct list *list)
+{
+    while (list && list->next)
+        list = list->next;
+    return list;
+}
+
+struct list *list_pop_front(struct list **list)
+{
+    struct list *popped = *list;
+
+    if (!popped)
+        return NULL;
+
+    *list = popped->next;
+    popped->next = NULL;
+
+    return popped;
+}
+
+void list_free(struct list *list, list_free_cb free_cb, void *userdata)
+{
+    struct list *popped;
+
+    while ((popped = list_pop_front(&list)) != NULL)
+    {
+        if (free_cb)
+            free_cb(popped->data, userdata);
+        free(popped);
+    }
+}
+
+#ifdef BUILD_TEST
+
+#include "test_util.h"
+
+TEST(list_init)
+{
+
+}
+
+TEST(list_new)
+{
+
+}
+
+TEST(list_append)
+{
+
+}
+
+TEST(list_get_last)
+{
+
+}
+
+TEST(list_pop_front)
+{
+
+}
+
+TEST(list_free)
+{
+
+}
+
+
+#endif
diff --git a/list.h b/list.h
new file mode 100644
index 0000000..ea82440
--- /dev/null
+++ b/list.h
@@ -0,0 +1,19 @@
+#ifndef LIST_H
+#define LIST_H
+
+struct list
+{
+    void *data;
+    struct list *next;
+};
+
+typedef void (*list_free_cb)(void *data, void *userdata);
+
+void list_init(struct list *list);
+struct list *list_new(void *data);
+struct list *list_append(struct list *list, void *data);
+struct list *list_get_last(struct list *list);
+struct list *list_pop_front(struct list **list);
+void list_free(struct list *list, list_free_cb free_cb, void *userdata);
+
+#endif
diff --git a/parse.c b/parse.c
new file mode 100644
index 0000000..b5101e1
--- /dev/null
+++ b/parse.c
@@ -0,0 +1,184 @@
+#include "parse.h"
+#include "tokens.h"
+#include "list.h"
+#include "atom.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+
+void print_list(struct list *list, int level)
+{
+    while (list)
+    {
+        struct atom *atom = LIST_GET_ATOM(list);
+
+        if (IS_TRUE(list))
+        {
+            printf("#t");
+        }
+        else if (IS_FALSE(list))
+        {
+            printf("#f");
+        }
+        else if (IS_NIL(list))
+        {
+            printf("nil");
+        }
+        else
+        {
+            switch (atom->type)
+            {
+                case ATOM_SYMBOL:
+                    printf("%.*s", atom->str.len, atom->str.str);
+                    break;
+
+                case ATOM_LIST:
+                    printf("(");
+                    print_list(atom->list, level+1);
+                    printf(")");
+                    break;
+
+                case ATOM_STR:
+                    printf("\"%.*s\"", atom->str.len, atom->str.str);
+                    break;
+
+                case ATOM_INT:
+                    printf("%ld", atom->l);
+            }
+        }
+
+        if (list->next)
+            printf(" ");
+
+        list = list->next;
+    }
+
+    if (level == 0)
+        printf("\n");
+}
+
+int parse_next(const char *src, int *pos, struct atom **result)
+{
+    struct token token;
+    int rc;
+
+    if ((rc = get_next_token(src, pos, &token)) > 0)
+    {
+        switch (token.type)
+        {
+            case TOKEN_INT:
+                *result = atom_new_int(strtol(token.s, NULL, 10));
+                break;
+
+            case TOKEN_STR:
+                *result = atom_new_str(token.s, token.len);
+                break;
+
+            case TOKEN_SYMBOL:
+                if (strncmp(token.s, "#t", 2) == 0)
+                    *result = &true_atom;
+                else if (strncmp(token.s, "#f", 2) == 0)
+                    *result = &false_atom;
+                else
+                    *result = atom_new_sym(token.s, token.len);
+                break;
+
+            case TOKEN_LPAREN:
+            {
+                struct list *l = parse(src, pos);
+                *result = atom_new_list(l);
+                break;
+            }
+
+            case TOKEN_RPAREN:
+                return -2;
+
+            case TOKEN_QUOTE:
+            {
+                struct atom *quoted = NULL;
+
+                parse_next(src, pos, &quoted);
+
+                struct list *qlist = list_append(NULL,
+                    atom_new_sym("quote", 5));
+
+                list_append(qlist, quoted);
+
+                *result = atom_new_list(qlist);
+
+                break;
+            }
+        }
+    }
+
+    return rc;
+}
+
+struct list *parse(const char *src, int *pos)
+{
+    int rc;
+    struct atom *atom;
+    struct list root, *last = &root;
+
+    list_init(last);
+
+    while ((rc = parse_next(src, pos, &atom)))
+    {
+        if (rc < 0)
+            break;
+
+        last = list_append(last, atom);
+    }
+
+    if (rc < 0 && rc != -2)
+        return NULL;
+
+    return root.next;
+}
+
+#ifdef BUILD_TEST
+
+#include "test_util.h"
+
+static const char *test_src_fact =
+    "(define fact\n"
+    "    ;; Factorial function\n"
+    "    (lambda (n)\n"
+    "        (if (eq n 0)\n"
+    "            1 ; Factorial of 0 is 1\n"
+    "            (* n (fact (- n 1))))))\n"
+    "(fact 5) ;; this should evaluate to 120\n";
+
+#define ASSERT_SYM(LIST, SYM) \
+    ASSERT_TRUE(IS_SYM(LIST)); \
+    ASSERT_STREQ(SYM, LIST_GET_ATOM(LIST)->str.str)
+
+TEST(test_parse)
+{
+    int pos = 0;
+    struct list *list;
+
+    list = parse(test_src_fact, &pos);
+
+    ASSERT_TRUE(list != NULL);
+
+    ASSERT_TRUE(IS_LIST(list));
+
+    list = LIST_GET_ATOM(list)->list;
+
+    ASSERT_TRUE(list != NULL);
+    ASSERT_SYM(list, "define");
+
+    list = list->next;
+
+    ASSERT_TRUE(list != NULL);
+    ASSERT_SYM(list, "fact");
+
+    list = list->next;
+
+    ASSERT_TRUE(list != NULL);
+}
+
+#endif
diff --git a/parse.h b/parse.h
new file mode 100644
index 0000000..94d6fa8
--- /dev/null
+++ b/parse.h
@@ -0,0 +1,12 @@
+#ifndef PARSER_H
+#define PARSER_H
+
+struct atom;
+struct list;
+
+int parse_next(const char *src, int *pos, struct atom **result);
+struct list *parse(const char *src, int *pos);
+
+void print_list(struct list *list, int level);
+
+#endif
diff --git a/repl.c b/repl.c
new file mode 100644
index 0000000..c9ddb6a
--- /dev/null
+++ b/repl.c
@@ -0,0 +1,27 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "parse.h"
+#include "eval.h"
+#include "list.h"
+#include "linenoise.h"
+
+int main(int argc, char **argv)
+{
+    char *line;
+
+    linenoiseSetMultiLine(0);
+
+    while ((line = linenoise("> ")) != NULL)
+    {
+        linenoiseHistoryAdd(line);
+
+        struct list *result = eval_str(line);
+
+        print_list(result, 0);
+
+        free(line);
+    }
+
+    return 0;
+}
diff --git a/test_util.h b/test_util.h
new file mode 100644
index 0000000..1ebf696
--- /dev/null
+++ b/test_util.h
@@ -0,0 +1,93 @@
+#ifndef TEST_UTIL_H
+#define TEST_UTIL_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef _MSC_VER
+
+#define CCALL __cdecl
+#pragma section(".CRT$XCU",read)
+#define INITIALIZER(f) \
+   static void __cdecl f(void); \
+   __declspec(allocate(".CRT$XCU")) void (__cdecl*f##_)(void) = f; \
+   static void __cdecl f(void)
+
+#elif defined(__GNUC__)
+
+#define CCALL
+#define INITIALIZER(f) \
+   static void f(void) __attribute__((constructor)); \
+   static void f(void)
+
+#endif
+
+// __attribute__((constructor)) static void test_##NAME##_init()
+
+#define TEST(NAME) \
+    static void test_##NAME(); \
+    void test_util_add_test(const char *name, void (*func)()); \
+    INITIALIZER(test_##NAME##_init) \
+    { \
+        test_util_add_test(#NAME, &test_##NAME); \
+    } \
+    static void test_##NAME()
+
+#define TEST_MAIN() \
+    typedef void (*test_func)(); \
+    struct test_def { \
+        const char *name; \
+        test_func func; \
+        struct test_def *next; \
+    }; \
+    static struct test_def test_defs; \
+    void test_util_add_test(const char *name, void (*func)()) \
+    { \
+        struct test_def *def = calloc(1, sizeof(*def)); \
+        struct test_def *last = &test_defs; \
+        while (last && last->next) last = last->next; \
+        last->next = def; \
+        def->name = strdup(name); \
+        def->func = func; \
+    } \
+    int main() \
+    { \
+        struct test_def *def = test_defs.next; \
+        while (def) \
+        { \
+            printf("running test %s\n", def->name); \
+            def->func(); \
+            def = def->next; \
+        } \
+        return 0; \
+    }
+
+#define ASSERT(X) \
+    do { \
+        if (!(X)) { \
+            fprintf(stderr, "assertion %s failed at %s:%d\n", \
+                    #X, __FILE__, __LINE__); \
+            exit(1); \
+        } \
+    } while (0)
+
+#define ASSERT_MSG(X, FMT, ...) \
+    do { \
+        if (!(X)) { \
+            fprintf(stderr, "assertion %s failed at %s:%d (" FMT ")\n", \
+                    #X, __FILE__, __LINE__, ##__VA_ARGS__); \
+            exit(1); \
+        } \
+    } while (0)
+
+#define ASSERT_TRUE(X) ASSERT(X)
+#define ASSERT_FALSE(X) ASSERT(!(X))
+
+#define ASSERT_EQ(EXPECTED, ACTUAL) ASSERT(((EXPECTED) == (ACTUAL)))
+#define ASSERT_NEQ(EXPECTED, ACTUAL) ASSERT(((EXPECTED) != (ACTUAL)))
+
+#define ASSERT_STREQ(EXPECTED, ACTUAL) ASSERT(strcmp((EXPECTED), (ACTUAL)) == 0)
+#define ASSERT_STREQ_N(EXPECTED, ACTUAL, N) ASSERT(strncmp((EXPECTED), (ACTUAL), (N)) == 0)
+
+#endif
diff --git a/tokens.c b/tokens.c
new file mode 100644
index 0000000..d249393
--- /dev/null
+++ b/tokens.c
@@ -0,0 +1,188 @@
+#include "tokens.h"
+
+#include <ctype.h>
+
+int get_next_token(const char *src, int *pos, struct token *token)
+{
+    char c;
+
+start:
+
+    while (isspace(src[*pos]))
+    {
+        *pos += 1;
+    }
+
+    c = src[*pos];
+
+    if (!c)
+        return 0;
+
+    if (c == ';')
+    {
+        *pos += 1;
+        while (src[*pos] != '\n')
+        {
+            *pos += 1;
+        }
+
+        goto start;
+    }
+
+    if (c == '(')
+    {
+        token->type = TOKEN_LPAREN;
+        token->s = &src[*pos];
+        token->len = 1;
+        *pos += 1;
+    }
+    else if (c == ')')
+    {
+        token->type = TOKEN_RPAREN;
+        token->s = &src[*pos];
+        token->len = 1;
+        *pos += 1;
+    }
+    else if (c == '.')
+    {
+        token->type = TOKEN_PERIOD;
+        token->s = &src[*pos];
+        token->len = 1;
+        *pos += 1;
+    }
+    else if (c == '\'')
+    {
+        token->type = TOKEN_QUOTE;
+        token->s = &src[*pos];
+        token->len = 1;
+        *pos += 1;
+    }
+    else if (isdigit(c))
+    {
+        token->type = TOKEN_INT;
+        token->s = &src[*pos];
+
+        while (!isspace(src[*pos]))
+        {
+            if (isdigit(src[*pos]))
+            {
+                *pos += 1;
+            }
+            else
+            {
+                c = src[*pos];
+
+                if (c == '(' || c == ')')
+                {
+                    break;
+                }
+
+                return -1;
+            }
+        }
+
+        token->len = &src[*pos] - token->s;
+    }
+    else if (c == '"')
+    {
+        *pos += 1;
+        token->type = TOKEN_STR;
+        token->s = &src[*pos];
+
+        while (src[*pos] != '"')
+        {
+            *pos += 1;
+        }
+
+        token->len = &src[*pos] - token->s;
+
+        *pos += 1;
+    }
+    else if (isalnum(c) || ispunct(c))
+    {
+        token->type = TOKEN_SYMBOL;
+        token->s = &src[*pos];
+        *pos += 1;
+
+        while ((isalnum(src[*pos]) || ispunct(src[*pos])) && src[*pos] != '(' && src[*pos] != ')')
+        {
+            *pos += 1;
+        }
+
+        token->len = &src[*pos] - token->s;
+    }
+    else
+    {
+        return -1;
+    }
+
+    return 1;
+}
+
+#ifdef BUILD_TEST
+
+#include "test_util.h"
+
+static const char *test_src_fact =
+    "(define fact\n"
+    "    ;; Factorial function\n"
+    "    (lambda (n)\n"
+    "        (if (eq n 0)\n"
+    "            1 ; Factorial of 0 is 1\n"
+    "            (* n (fact (- n 1))))))\n"
+    "(fact 5) ;; this should evaluate to 120\n";
+
+TEST(test_get_next_token)
+{
+    int pos = 0;
+
+    struct token token;
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_LPAREN, token.type);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_SYMBOL, token.type);
+    ASSERT_STREQ_N("define", token.s, 6);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_SYMBOL, token.type);
+    ASSERT_STREQ_N("fact", token.s, 4);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_LPAREN, token.type);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_SYMBOL, token.type);
+    ASSERT_STREQ_N("lambda", token.s, 6);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_LPAREN, token.type);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_SYMBOL, token.type);
+    ASSERT_STREQ_N("n", token.s, 1);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_RPAREN, token.type);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_INT, token.type);
+    ASSERT_STREQ_N("0", token.s, 1);
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+
+    ASSERT_EQ(1, get_next_token(test_src_fact, &pos, &token));
+    ASSERT_EQ(TOKEN_SYMBOL, token.type);
+    ASSERT_STREQ_N("*", token.s, 1);
+}
+
+#endif /* BUILD_TEST */
diff --git a/tokens.h b/tokens.h
new file mode 100644
index 0000000..8b06454
--- /dev/null
+++ b/tokens.h
@@ -0,0 +1,24 @@
+#ifndef TOKENS_H
+#define TOKENS_H
+
+enum
+{
+    TOKEN_INT,
+    TOKEN_STR,
+    TOKEN_SYMBOL,
+    TOKEN_LPAREN,
+    TOKEN_RPAREN,
+    TOKEN_PERIOD,
+    TOKEN_QUOTE
+};
+
+struct token
+{
+    const char *s;
+    int len;
+    int type;
+};
+
+int get_next_token(const char *src, int *pos, struct token *token);
+
+#endif
diff --git a/tst_main.c b/tst_main.c
new file mode 100644
index 0000000..6e99cac
--- /dev/null
+++ b/tst_main.c
@@ -0,0 +1,2 @@
+#include "test_util.h"
+TEST_MAIN()