feat(Parser): skip comments along with whitespace and commas

Fixes #4.
utkarshkukreti · Aug 3, 2018 · eaeaab8 · eaeaab8
1 parent 42f24fa
commit eaeaab8
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Showing 2 changed files with 44 additions and 3 deletions.
diff --git a/src/parser.rs b/src/parser.rs
@@ -26,7 +26,7 @@ impl<'a> Parser<'a> {
     }
 
     pub fn read(&mut self) -> Option<Result<Value, Error>> {
-        self.advance_while(|ch| ch.is_whitespace() || ch == ',');
+        self.whitespace();
 
         self.chars.clone().next().map(|(pos, ch)| match (pos, ch) {
             (start, '0'...'9') => {
@@ -149,7 +149,7 @@ impl<'a> Parser<'a> {
                 self.chars.next();
                 let mut items = vec![];
                 loop {
-                    self.advance_while(|ch| ch.is_whitespace() || ch == ',');
+                    self.whitespace();
 
                     if self.peek() == Some(close) {
                         self.chars.next();
@@ -201,7 +201,8 @@ impl<'a> Parser<'a> {
                         let close = '}';
                         let mut items = vec![];
                         loop {
-                            self.advance_while(|ch| ch.is_whitespace() || ch == ',');
+                            self.whitespace();
+
                             if self.peek() == Some(close) {
                                 self.chars.next();
                                 return Ok(Value::Set(items.into_iter().collect()));
@@ -264,6 +265,21 @@ impl<'a> Parser<'a> {
         self.chars.clone().next().map(|(_, ch)| ch)
     }
 
+    fn whitespace(&mut self) {
+        loop {
+            // Skip whitespace.
+            self.advance_while(|ch| ch.is_whitespace() || ch == ',');
+            // Skip comment if present.
+            if self.chars.clone().next().map_or(false, |(_, ch)| ch == ';') {
+                self.advance_while(|ch| ch != '\n');
+                self.chars.next();
+            } else {
+                // Otherwise we're done.
+                return;
+            }
+        }
+    }
+
     fn advance_while<F: FnMut(char) -> bool>(&mut self, mut f: F) -> usize {
         loop {
             match self.chars.clone().next() {

diff --git a/tests/parser_tests.rs b/tests/parser_tests.rs
@@ -505,3 +505,28 @@ fn test_tagged_values() {
 
     assert_eq!(parser.read(), None);
 }
+
+#[test]
+fn test_comments() {
+    use std::collections::BTreeMap;
+
+    let mut parser = Parser::new(
+        "
+        ; 0
+        ;; ;
+        0
+        --;0
+        +0
+        [;[]
+        ]
+        {;}
+        }
+    ",
+    );
+    assert_eq!(parser.read(), Some(Ok(Value::Integer(0))));
+    assert_eq!(parser.read(), Some(Ok(Value::Symbol("--".into()))));
+    assert_eq!(parser.read(), Some(Ok(Value::Integer(0))));
+    assert_eq!(parser.read(), Some(Ok(Value::Vector(Vec::new()))));
+    assert_eq!(parser.read(), Some(Ok(Value::Map(BTreeMap::new()))));
+    assert_eq!(parser.read(), None);
+}