Roughing out pratt parser logic

examples/acme_parser.rs

@@ -7,24 +7,21 @@ use datafusion_sql::ansi::tokenizer::ANSISQLTokenizer;
 use datafusion_sql::tokenizer::*;
 use datafusion_sql::parser::*;
 
-///
 /// This example demonstrates building a custom ACME parser that extends the generic parser
-/// by adding support for a factorial operator !!
-///
+/// by adding support for a factorial expression `!! expr`.
 
+/// Custom SQLToken
 #[derive(Debug,PartialEq)]
 enum AcmeToken {
-    /// Factorial operator `!!`
+    /// Factorial token `!!`
     Factorial
 }
 
+/// Custom SQLExpr
 #[derive(Debug)]
-enum AcmeOperator {
-    Factorial
-}
-
-#[derive(Debug)]
-enum AcmeTokenizerError {
+enum AcmeExpr {
+    /// Factorial expression
+    Factorial(Box<SQLExpr<AcmeExpr>>)
 }
 
 struct AcmeTokenizer {
@@ -34,6 +31,10 @@ struct AcmeTokenizer {
 /// The ACME tokenizer looks for the factorial operator `!!` but delegates everything else
 impl SQLTokenizer<AcmeToken> for AcmeTokenizer {
 
+    fn precedence(&self, token: &SQLToken<AcmeToken>) -> usize {
+        unimplemented!()
+    }
+
     fn peek_token(&self, chars: &mut Peekable<Chars>) -> Result<Option<SQLToken<AcmeToken>>, TokenizerError<AcmeToken>> {
         unimplemented!()
     }
@@ -53,7 +54,7 @@ impl SQLTokenizer<AcmeToken> for AcmeTokenizer {
                         },
                         None => Ok(Some(SQLToken::Not))
                     }
-                },
+                }
                 _ => self.generic.next_token(chars)
             }
             _ => self.generic.next_token(chars)
@@ -61,19 +62,47 @@ impl SQLTokenizer<AcmeToken> for AcmeTokenizer {
     }
 }
 
+struct AcmeParser<'a> {
+    chars: Peekable<Chars<'a>>
+}
+
+impl<'a> AcmeParser<'a> {
+
+    pub fn new(sql: &'a str) -> Self {
+        AcmeParser {
+            chars: sql.chars().peekable()
+        }
+    }
+}
+
+impl<'a> SQLParser<AcmeToken, AcmeExpr> for AcmeParser<'a> {
+
+    fn parse_prefix(&mut self) -> Result<Box<SQLExpr<AcmeExpr>>, ParserError<AcmeToken>> {
+        unimplemented!()
+    }
+
+    fn parse_infix(&mut self, left: &SQLExpr<AcmeExpr>, precedence: usize) -> Result<Option<Box<SQLExpr<AcmeExpr>>>, ParserError<AcmeToken>> {
+        unimplemented!()
+    }
+}
 
 
 fn main() {
 
     let sql = "1 + !! 5 * 2";
 
-    let mut acme_tokenizer = AcmeTokenizer {
-        generic: ANSISQLTokenizer { }
-    };
+    let acme_parser = AcmeParser::new(sql);
 
-    let tokens = tokenize(&sql, &mut acme_tokenizer).unwrap();
 
-    println!("tokens = {:?}", tokens);
+    //acme_parser
+
+//    let mut acme_tokenizer = AcmeTokenizer {
+//        generic: ANSISQLTokenizer { }
+//    };
+//
+//    let tokens = tokenize(&sql, &mut acme_tokenizer).unwrap();
+//
+//    println!("tokens = {:?}", tokens);