create Chars struct instead of using Peekable

examples/acme_parser.rs

@@ -35,40 +35,30 @@ impl SQLTokenizer<AcmeToken> for AcmeTokenizer {
         unimplemented!()
     }
 
-    fn peek_token(&mut self) -> Result<Option<SQLToken<AcmeToken>>, TokenizerError<AcmeToken>> {
+    fn next_token(&mut self) -> Result<Option<SQLToken<AcmeToken>>, TokenizerError> {
+//        let mut arc = self.ansi_tokenizer.lock().unwrap();
+//        match arc.peek_char() {
+//            Some(&ch) => match ch {
+//                '!' => {
+//                    arc.next_char(); // consume the first `!`
+//                    match arc.peek_char() {
+//                        Some(&ch) => match ch {
+//                            '!' => {
+//                                arc.next_char(); // consume the second `!`
+//                                Ok(Some(SQLToken::Custom(AcmeToken::Factorial)))
+//                            },
+//                            _ => Err(TokenizerError::UnexpectedChar(ch,Position::new(0,0)))
+//                        },
+//                        None => Ok(Some(SQLToken::Not))
+//                    }
+//                }
+//                _ => arc.next_token()
+//            }
+//            _ => arc.next_token()
+//        }
         unimplemented!()
     }
 
-    fn next_token(&mut self) -> Result<Option<SQLToken<AcmeToken>>, TokenizerError<AcmeToken>> {
-        let mut arc = self.ansi_tokenizer.lock().unwrap();
-        match arc.peek_char() {
-            Some(&ch) => match ch {
-                '!' => {
-                    arc.next_char(); // consume the first `!`
-                    match arc.peek_char() {
-                        Some(&ch) => match ch {
-                            '!' => {
-                                arc.next_char(); // consume the second `!`
-                                Ok(Some(SQLToken::Custom(AcmeToken::Factorial)))
-                            },
-                            _ => Err(TokenizerError::UnexpectedChar(ch,Position::new(0,0)))
-                        },
-                        None => Ok(Some(SQLToken::Not))
-                    }
-                }
-                _ => arc.next_token()
-            }
-            _ => arc.next_token()
-        }
-    }
-
-    fn peek_char(&mut self) -> Option<&char> {
-        unimplemented!()
-    }
-
-    fn next_char(&mut self) -> Option<&char> {
-        unimplemented!()
-    }
 }
 
 struct AcmeParser {

src/ansi/parser.rs

@@ -24,7 +24,7 @@ impl<TokenType, ExprType> SQLParser<TokenType, ExprType> for ANSISQLParser<Token
 
     fn parse_prefix(&mut self) -> Result<Box<SQLExpr<ExprType>>, ParserError<TokenType>> {
 
-        match self.tokenizer.lock().unwrap().peek_token()? {
+        match self.tokenizer.lock().unwrap().next_token()? {
             Some(SQLToken::Keyword(ref k)) => match k.to_uppercase().as_ref() {
                 "INSERT" => unimplemented!(),
                 "UPDATE" => unimplemented!(),

src/ansi/tokenizer.rs

@@ -16,11 +16,7 @@ impl<'a, TokenType> SQLTokenizer<TokenType> for ANSISQLTokenizer<'a>
         unimplemented!()
     }
 
-    fn peek_token(&mut self) -> Result<Option<SQLToken<TokenType>>, TokenizerError<TokenType>> {
+    fn next_token(&mut self) -> Result<Option<SQLToken<TokenType>>, TokenizerError> {
-        unimplemented!()
-    }
-
-    fn next_token(&mut self) -> Result<Option<SQLToken<TokenType>>, TokenizerError<TokenType>> {
         match self.chars.next() {
             Some(ch) => match ch {
                 ' ' | '\t' | '\n' => Ok(Some(SQLToken::Whitespace(ch))),
@@ -48,12 +44,5 @@ impl<'a, TokenType> SQLTokenizer<TokenType> for ANSISQLTokenizer<'a>
         }
     }
 
-    fn peek_char(&mut self) -> Option<&char> {
-        unimplemented!()
-    }
-
-    fn next_char(&mut self) -> Option<&char> {
-        unimplemented!()
-    }
 }
 

src/parser.rs

@@ -1,8 +1,6 @@
 use std::cmp::PartialEq;
 use std::fmt::Debug;
 use std::rc::Rc;
-use std::str::Chars;
-use std::iter::Peekable;
 use std::sync::{Arc, Mutex};
 
 use super::tokenizer::*;
@@ -99,10 +97,10 @@ pub enum ParserError<TokenType>
     Custom(String)
 }
 
-impl<TokenType> From<TokenizerError<TokenType>> for ParserError<TokenType>
+impl<TokenType> From<TokenizerError> for ParserError<TokenType>
     where TokenType: Debug + PartialEq {
 
-    fn from(_: TokenizerError<TokenType>) -> Self {
+    fn from(_: TokenizerError) -> Self {
         unimplemented!()
     }
 }

src/tokenizer.rs

@@ -3,6 +3,41 @@ use std::fmt::Debug;
 //use std::iter::Peekable;
 //use std::str::Chars;
 
+
+pub struct CharSeq {
+    chars: Vec<char>,
+    i: usize,
+    m: usize
+}
+
+impl CharSeq {
+
+    pub fn new(sql: &str) -> Self {
+        CharSeq {
+            chars: sql.chars().collect(),
+            i: 0,
+            m: 0
+        }
+    }
+
+    pub fn mark(&mut self) {
+        self.m = self.i;
+    }
+
+    pub fn reset(&mut self) {
+        self.i = self.m;
+    }
+
+    pub fn next(&mut self) -> Option<char> {
+        if self.i < self.chars.len() {
+            self.i += 1;
+            Some(self.chars[self.i-1])
+        } else {
+            None
+        }
+    }
+}
+
 #[derive(Debug)]
 pub struct Position {
     line: usize,
@@ -15,11 +50,11 @@ impl Position {
 }
 
 #[derive(Debug)]
-pub enum TokenizerError<T> {
+pub enum TokenizerError {
     UnexpectedChar(char,Position),
     UnexpectedEof(Position),
     UnterminatedStringLiteral(Position),
-    Custom(T)
+    Custom(String)
 }
 
 /// SQL Tokens
@@ -43,7 +78,7 @@ pub enum SQLToken<T: Debug + PartialEq> {
     LParen,
     RParen,
     Comma,
-    /// Custom token
+    /// Custom token (dialect-specific)
     Custom(T)
 }
 
@@ -53,15 +88,8 @@ pub trait SQLTokenizer<TokenType>
     /// get the precendence of a token
     fn precedence(&self, token: &SQLToken<TokenType>) -> usize;
 
-    /// return a reference to the next token but do not advance the index
-    fn peek_token(&mut self) -> Result<Option<SQLToken<TokenType>>, TokenizerError<TokenType>>;
-
     /// return a reference to the next token and advance the index
-    fn next_token(&mut self) -> Result<Option<SQLToken<TokenType>>, TokenizerError<TokenType>>;
+    fn next_token(&mut self) -> Result<Option<SQLToken<TokenType>>, TokenizerError>;
-
-    fn peek_char(&mut self) -> Option<&char>;
-
-    fn next_char(&mut self) -> Option<&char>;
 }
 
 //