Refactoring

Author: andygrove

examples/acme_parser.rs

@@ -107,7 +107,7 @@ fn main() {
 
     let mut pratt_parser = PrattParser {
         chars: CharSeq::new(sql),
-        parser: acme_parser
+        parsers: vec![acme_parser, ansi_parser]
     };
 
     let expr = pratt_parser.parse_expr().unwrap();

src/parser.rs

@@ -116,16 +116,26 @@ pub trait SQLParser<TokenType, ExprType>
 
 pub struct PrattParser<TokenType, ExprType> {
     pub chars: CharSeq,
-    pub parser: Arc<Mutex<SQLParser<TokenType, ExprType>>>
+    pub parsers: Vec<Arc<Mutex<SQLParser<TokenType, ExprType>>>>
 }
 
 impl<TokenType, ExprType> PrattParser<TokenType, ExprType> where TokenType: Debug + PartialEq, ExprType: Debug {
 
     pub fn parse_expr(&mut self) -> Result<Option<Box<SQLExpr<ExprType>>>, ParserError<TokenType>> {
 
-        let mut p = self.parser.lock().unwrap();
+        for i in 0..self.parsers.len() {
+            let mut p = self.parsers[i].lock().unwrap();
+            let expr = p.parse_prefix(&mut self.chars)?;
 
-        p.parse_prefix(&mut self.chars)
+            // return as soon as we have a match
+            match expr {
+                Some(_) => return Ok(expr),
+                _ => {}
+            }
+        }
+
+        // found no valid token
+        Ok(None)
     }
 
 }