Rust: add step3_env

3 files changed, 240 insertions, 1 deletions

diff --git a/rust/src/env.rs b/rust/src/env.rs
new file mode 100644
index 0000000..9c98f23
--- /dev/null
+++ b/rust/src/env.rs
@@ -0,0 +1,44 @@
+use std::rc::Rc;
+use std::cell::RefCell;
+use std::collections::HashMap;
+
+use types::{MalVal,MalRet,Nil};
+
+struct EnvType {
+    data: HashMap<String,MalVal>,
+    outer: Option<Env>,
+}
+
+pub type Env = Rc<RefCell<EnvType>>;
+
+pub fn env_new(outer: Option<Env>) -> Env {
+    Rc::new(RefCell::new(EnvType{data: HashMap::new(), outer: outer}))
+}
+
+pub fn env_find(env: Env, key: String) -> Option<Env> {
+    if env.borrow().data.contains_key(&key) {
+        Some(env)
+    } else {
+        match env.borrow().outer {
+            Some(ref e) => env_find(e.clone(), key),
+            None => None,
+        }
+    }
+}
+
+pub fn env_set(env: &Env, key: String, val: MalVal) {
+    env.borrow_mut().data.insert(key, val.clone());
+}
+
+pub fn env_get(env: Env, key: String) -> MalRet {
+    match env_find(env, key.clone()) {
+        Some(e) => {
+            match e.borrow().data.find_copy(&key) {
+                Some(v) => Ok(v),
+                None => Ok(Rc::new(Nil)),
+            }
+        },
+        None    => Ok(Rc::new(Nil)),
+    }
+}
+
diff --git a/rust/src/step2_eval.rs b/rust/src/step2_eval.rs
index 5df9a94..8d28a0f 100644
--- a/rust/src/step2_eval.rs
+++ b/rust/src/step2_eval.rs
@@ -6,6 +6,7 @@ extern crate regex;
 
 use std::rc::Rc;
 use std::collections::HashMap;
+
 use types::{MalVal,MalRet,Nil,Int,Sym,List,Func};
 mod readline;
 mod types;
@@ -21,7 +22,7 @@ fn read(str: String) -> MalRet {
 fn eval_ast(ast: MalVal, env: &HashMap<String,MalVal>) -> MalRet {
     match *ast {
         Sym(ref sym) => {
-            match (*env).find_copy(sym) {
+            match env.find_copy(sym) {
                 Some(mv) => Ok(mv),
                 None     => Ok(Rc::new(Nil)),
             }
diff --git a/rust/src/step3_env.rs b/rust/src/step3_env.rs
new file mode 100644
index 0000000..c827cb5
--- /dev/null
+++ b/rust/src/step3_env.rs
@@ -0,0 +1,194 @@
+// support precompiled regexes in reader.rs
+#![feature(phase)]
+#[phase(plugin)]
+extern crate regex_macros;
+extern crate regex;
+
+use std::rc::Rc;
+
+use types::{MalVal,MalRet,Int,Sym,List,Vector,Func};
+use env::{Env,env_new,env_set,env_get};
+mod readline;
+mod types;
+mod reader;
+mod printer;
+mod env;
+
+// read
+fn read(str: String) -> MalRet {
+    reader::read_str(str)
+}
+
+// eval
+fn eval_ast(ast: MalVal, env: Env) -> MalRet {
+    let ast2 = ast.clone();
+    match *ast2 {
+    //match *ast {
+        Sym(ref sym) => {
+            env_get(env.clone(), sym.clone())
+        },
+        List(ref a) => {
+            let mut ast_vec : Vec<MalVal> = vec![];
+            for mv in a.iter() {
+                let mv2 = mv.clone();
+                match eval(mv2, env.clone()) {
+                    Ok(mv) => { ast_vec.push(mv); },
+                    Err(e) => { return Err(e); },
+                }
+            }
+            Ok(Rc::new(List(ast_vec)))
+        },
+        _ => {
+            Ok(ast)
+        }
+    }
+    /*
+    Ok(ast)
+    */
+}
+
+fn eval(ast: MalVal, env: Env) -> MalRet {
+    let ast2 = ast.clone();
+    match *ast2 {
+        List(_) => (),  // continue
+        _ => return eval_ast(ast2, env),
+    }
+
+    // apply list
+    match *ast2 {
+        List(ref args) => {
+            let ref a0 = *args[0];
+            match *a0 {
+                Sym(ref a0sym) => {
+                    match a0sym.as_slice() {
+                        "def!" => {
+                            let a1 = (*args)[1].clone();
+                            let a2 = (*args)[2].clone();
+                            let res = eval(a2, env.clone());
+                            match res {
+                                Ok(r) => {
+                                    match *a1 {
+                                        Sym(ref s) => {
+                                            env_set(&env.clone(), s.clone(), r.clone());
+                                            return Ok(r);
+                                        },
+                                        _ => {
+                                            return Err("def! of non-symbol".to_string())
+                                        }
+                                    }
+                                },
+                                Err(e) => return Err(e),
+                            }
+                        },
+                        "let*" => {
+                            let let_env = env_new(Some(env.clone()));
+                            let a1 = (*args)[1].clone();
+                            let a2 = (*args)[2].clone();
+                            match *a1 {
+                                List(ref binds) | Vector(ref binds) => {
+                                    let mut it = binds.iter();
+                                    while it.len() >= 2 {
+                                        let b = it.next().unwrap();
+                                        let exp = it.next().unwrap();
+                                        match **b {
+                                            Sym(ref bstr) => {
+                                                match eval(exp.clone(), let_env.clone()) {
+                                                    Ok(r) => {
+                                                        env_set(&let_env, bstr.clone(), r);
+                                                    },
+                                                    Err(e) => {
+                                                        return Err(e);
+                                                    },
+                                                }
+                                            },
+                                            _ => {
+                                                return Err("let* with non-symbol binding".to_string());
+                                            },
+                                        }
+                                    }
+                                },
+                                _ => return Err("let* with non-list bindings".to_string()),
+                            }
+                            return eval(a2, let_env.clone());
+                        },
+                        _ => ()
+                    }
+                }
+                _ => (),
+            }
+            // function call
+            match eval_ast(ast, env) {
+                Err(e) => Err(e),
+                Ok(el) => {
+                    match *el {
+                        List(ref args) => {
+                            // TODO: make this work
+                            //match args.as_slice() {
+                            //    [&Func(f), rest..] => {
+                            //        (*f)(rest.to_vec())
+                            //    },
+                            //    _ => Err("attempt to call non-function".to_string()),
+                            //}
+                            let args2 = args.clone();
+                            match *args2[0] {
+                                Func(f) => f(args.slice(1,args.len()).to_vec()),
+                                _ => Err("attempt to call non-function".to_string()),
+                            }
+                        }
+                        _ => Err("Invalid apply".to_string()),
+                    }
+                }
+            }
+        }
+        _ => Err("Expected list".to_string()),
+    }
+}
+
+// print
+fn print(exp: MalVal) -> String {
+    exp.pr_str(true)
+}
+
+fn rep(str: String, env: Env) -> Result<String,String> {
+    match read(str) {
+        Err(e) => Err(e),
+        Ok(ast) => {
+            //println!("read: {}", ast);
+            match eval(ast, env) {
+                Err(e)  => Err(e),
+                Ok(exp) => Ok(print(exp)),
+            }
+        }
+    }
+}
+
+fn int_op(f: |i:int,j:int|-> int, a:Vec<MalVal>) -> MalRet {
+    match *a[0] {
+        Int(a0) => match *a[1] {
+            Int(a1) => Ok(Rc::new(Int(f(a0,a1)))),
+            _ => Err("second arg must be an int".to_string()),
+        },
+        _ => Err("first arg must be an int".to_string()),
+    }
+}
+fn add(a:Vec<MalVal>) -> MalRet { int_op(|i,j| { i+j }, a) }
+fn sub(a:Vec<MalVal>) -> MalRet { int_op(|i,j| { i-j }, a) }
+fn mul(a:Vec<MalVal>) -> MalRet { int_op(|i,j| { i*j }, a) }
+fn div(a:Vec<MalVal>) -> MalRet { int_op(|i,j| { i/j }, a) }
+
+fn main() {
+    let repl_env = env_new(None);
+    env_set(&repl_env, "+".to_string(), Rc::new(Func(add)));
+    env_set(&repl_env, "-".to_string(), Rc::new(Func(sub)));
+    env_set(&repl_env, "*".to_string(), Rc::new(Func(mul)));
+    env_set(&repl_env, "/".to_string(), Rc::new(Func(div)));
+
+    loop {
+        let line = readline::mal_readline("user> ");
+        match line { None => break, _ => () }
+        match rep(line.unwrap(), repl_env.clone()) {
+            Ok(str)  => println!("{}", str),
+            Err(str) => println!("Error: {}", str),
+        }
+    }
+}