significant refactor and simplification

src/lex.rs

@@ -23,7 +23,7 @@ const UNMATCHED_LIST_DELIM: &str = "Unmatched list delimiter in input";
 /* takes a line of user input
  * returns an unsimplified tree of tokens.
  */
-pub fn lex<'a>(document: &'a String) -> Result<Box<Seg>, String> {
+pub fn lex(document: &String) -> Result<Box<Seg>, String> {
     if !document.is_ascii() {
         return Err("document may only contain ascii characters".to_string());
     }
@@ -42,7 +42,7 @@ pub fn lex<'a>(document: &'a String) -> Result<Box<Seg>, String> {
  * Returns Ok(Rc<Seg>) if lexing passes
  * Returns Err(String) if an error occurs
  */
-fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
+fn process(document: &String) -> Result<Box<Seg>, String> {
     let doc_len = document.len();
 
     if doc_len == 0 {
@@ -87,7 +87,7 @@ fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
                 // set alloc_list
                 if delim == ')' {
                     alloc_list = true;
-                    if ref_stack.len() < 1 {
+                    if ref_stack.is_empty() {
                         return Err("too many end parens".to_string());
                     }
                 }
@@ -101,7 +101,7 @@ fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
         // try to generalize all whitespace
         if !needs_alloc && char::is_whitespace(c) && !is_str {
             // dont make empty tokens just because the document has consecutive whitespace
-            if token.len() == 0 {
+            if token.is_empty() {
                 continue;
             }
             needs_alloc = true;
@@ -116,7 +116,7 @@ fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
                         continue;
                     }
 
-                    if token != "" {
+                    if !token.is_empty() {
                         return Err("list started in middle of another token".to_string());
                     }
 
@@ -147,7 +147,7 @@ fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
          * 2. Handle expansion of current list ref
          */
         } else {
-            if token.len() == 0 && !is_str && !alloc_list {
+            if token.is_empty() && !is_str && !alloc_list {
                 return Err("Empty token".to_string());
             }
 
@@ -158,7 +158,7 @@ fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
                 is_str = false;
                 token = String::new();
                 current_seg.append(obj);
-            } else if token.len() > 0 {
+            } else if !token.is_empty() {
                 if token == "true" {
                     obj = Box::from(Ctr::Bool(true));
                 } else if token == "false" {
@@ -179,7 +179,7 @@ fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
 
             if alloc_list {
                 // return if we have finished the document
-                if ref_stack.len() == 0 {
+                if ref_stack.is_empty() {
                     return Ok(Box::new(current_seg));
                 }
 
@@ -199,9 +199,10 @@ fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
     }
 
     if is_str {
-        return Err(UNMATCHED_STR_DELIM.to_string());
+        Err(UNMATCHED_STR_DELIM.to_string())
+    } else {
+        Err(UNMATCHED_LIST_DELIM.to_string())
     }
-    return Err(UNMATCHED_LIST_DELIM.to_string());
 }
 
 /* Returns true if token
@@ -209,13 +210,12 @@ fn process<'a>(document: &'a String) -> Result<Box<Seg>, String> {
  *
  * else returns false
  */
-fn tok_is_symbol(token: &String) -> Option<String> {
-    let tok = token.as_str();
-    for t in tok.chars() {
-        if !t.is_alphabetic() && !t.is_digit(10) && !(t == '-') && !(t == '_') {
+fn tok_is_symbol(token: &str) -> Option<String> {
+    for t in token.chars() {
+        if !t.is_alphanumeric() && t != '-' && t != '_' {
             return None;
         }
     }
 
-    return Some(String::from(tok));
+    Some(String::from(token))
 }