go: add readline.go that wraps libreadline/libedit

1 files changed, 70 insertions, 0 deletions

diff --git a/go/src/readline/readline.go b/go/src/readline/readline.go
new file mode 100644
index 0000000..2777cb4
--- /dev/null
+++ b/go/src/readline/readline.go
@@ -0,0 +1,70 @@
+package readline
+
+/*
+// IMPORTANT: choose one
+#cgo LDFLAGS: -ledit
+//#cgo LDFLAGS: -lreadline // NOTE: libreadline is GPL
+
+// free()
+#include <stdlib.h>
+// readline()
+#include <readline/readline.h>
+// add_history()
+#include <readline/history.h>
+*/
+import "C"
+
+import (
+    "errors"
+    "unsafe"
+    "strings"
+    "io/ioutil"
+    "os"
+    "path/filepath"
+    "fmt"
+)
+
+var HISTORY_FILE = ".mal-history"
+
+var rl_history_loaded = false
+
+func Readline(prompt string) (string, error) {
+    history_path := filepath.Join(os.Getenv("HOME"), "/", HISTORY_FILE)
+
+    if !rl_history_loaded {
+        rl_history_loaded = true
+        content, e := ioutil.ReadFile(history_path)
+        if e != nil { return "", e }
+
+        for _, add_line := range strings.Split(string(content), "\n") {
+            if add_line == "" { continue }
+            c_add_line := C.CString(add_line)
+            C.add_history(c_add_line)
+            C.free(unsafe.Pointer(c_add_line))
+        }
+    }
+
+
+    c_prompt := C.CString(prompt)
+    defer C.free(unsafe.Pointer(c_prompt))
+
+    c_line := C.readline(c_prompt)
+    defer C.free(unsafe.Pointer(c_line))
+    line := C.GoString(c_line)
+
+    if c_line == nil {
+        return "", errors.New("C.readline call failed")
+    }
+    C.add_history(c_line)
+
+    // append to file
+    f, e := os.OpenFile(history_path, os.O_APPEND|os.O_WRONLY, 0600) 
+    if e == nil {
+        defer f.Close()
+
+        _, e = f.WriteString(line+"\n")
+        if e != nil { fmt.Printf("error writing to history") }
+    }
+
+    return line, nil
+}