Some basic parsing works (fixing order of operations), and one test case.

src/syntax.rs

@@ -1,18 +1,22 @@
 use lalrpop_util::lalrpop_mod;
 
-mod tokens;
 mod token_stream;
+mod tokens;
 lalrpop_mod!(parser, "/syntax/parser.rs");
 mod ast;
 
 pub use crate::syntax::ast::*;
 use crate::syntax::parser::ProgramParser;
-use crate::syntax::tokens::Token;
 use crate::syntax::token_stream::{LexerError, Location, TokenStream};
+use crate::syntax::tokens::Token;
+#[cfg(test)]
+use crate::util::istring::InternedString;
 use lalrpop_util::ParseError;
 use std::fs;
 use std::io;
+use std::str::FromStr;
 
+#[derive(Debug)]
 pub enum ParserError {
     IOError(io::Error),
     ParseError(ParseError<Location, Token, LexerError>),
@@ -37,4 +41,51 @@ impl Program {
         let lexer = TokenStream::from_file(filename, &mut buffer)?;
         Ok(ProgramParser::new().parse(lexer)?)
     }
+
+    fn parse(filename: &str, buffer: &mut String) -> Result<Program, ParserError> {
+        let lexer = TokenStream::new(filename, buffer);
+        Ok(ProgramParser::new().parse(lexer)?)
+    }
+}
+
+impl FromStr for Program {
+    type Err = ParserError;
+
+    fn from_str(s: &str) -> Result<Program, ParserError> {
+        let mut s2 = s.to_string();
+        Program::parse("<from_str>", &mut s2)
+    }
+}
+
+#[test]
+fn order_of_operations() {
+    let muladd1 = "1 + 2 * 3";
+    let testfile = InternedString::new("<from_str>");
+    assert_eq!(
+        Program::from_str(muladd1).unwrap(),
+        Program {
+            statements: vec![],
+            result: Expression::Primitive(
+                Location::InFile(testfile, 2),
+                "+".to_string(),
+                vec![
+                    Expression::Value(Location::InFile(testfile, 0), Value::Number(None, 1)),
+                    Expression::Primitive(
+                        Location::InFile(testfile, 6),
+                        "*".to_string(),
+                        vec![
+                            Expression::Value(
+                                Location::InFile(testfile, 4),
+                                Value::Number(None, 2),
+                            ),
+                            Expression::Value(
+                                Location::InFile(testfile, 8),
+                                Value::Number(None, 3),
+                            ),
+                        ]
+                    )
+                ]
+            )
+        }
+    );
 }

src/syntax/ast.rs

@@ -1,21 +1,25 @@
 use crate::syntax::token_stream::Location;
 
+#[derive(Debug, PartialEq)]
 pub struct Program {
     pub statements: Vec<Statement>,
     pub result: Expression,
 }
 
+#[derive(Debug, PartialEq)]
 pub enum Statement {
     Binding(Location, String, Expression),
     Expr(Location, Expression),
 }
 
+#[derive(Debug, PartialEq)]
 pub enum Expression {
     Value(Location, Value),
     Reference(Location, String),
     Primitive(Location, String, Vec<Expression>),
 }
 
+#[derive(Debug, PartialEq)]
 pub enum Value {
-    Number(Option<u8>, i128)
+    Number(Option<u8>, i128),
 }

src/syntax/parser.lalrpop

@@ -46,18 +46,18 @@ Statement: Statement = {
 }
 
 Expression: Expression = {
-    MultiplicativeExpression
-}
-
-MultiplicativeExpression: Expression = {
-    <l:@L> <e1:MultiplicativeExpression> "*" <e2:AdditiveExpression> => Expression::Primitive(l, "*".to_string(), vec![e1, e2]),
-    <l:@L> <e1:MultiplicativeExpression> "/" <e2:AdditiveExpression> => Expression::Primitive(l, "/".to_string(), vec![e1, e2]),
     AdditiveExpression,
 }
 
 AdditiveExpression: Expression = {
-    <l:@L> <e1:AdditiveExpression> "+" <e2:AtomicExpression> => Expression::Primitive(l, "*".to_string(), vec![e1, e2]),
+    <e1:AdditiveExpression> <l:@L> "+" <e2:MultiplicativeExpression> => Expression::Primitive(l, "+".to_string(), vec![e1, e2]),
-    <l:@L> <e1:AdditiveExpression> "-" <e2:AtomicExpression> => Expression::Primitive(l, "/".to_string(), vec![e1, e2]),
+    <e1:AdditiveExpression> <l:@L> "-" <e2:MultiplicativeExpression> => Expression::Primitive(l, "-".to_string(), vec![e1, e2]),
+    MultiplicativeExpression,
+}
+
+MultiplicativeExpression: Expression = {
+    <e1:MultiplicativeExpression> <l:@L> "*" <e2:AtomicExpression> => Expression::Primitive(l, "*".to_string(), vec![e1, e2]),
+    <e1:MultiplicativeExpression> <l:@L> "/" <e2:AtomicExpression> => Expression::Primitive(l, "/".to_string(), vec![e1, e2]),
     AtomicExpression,
 }
 

src/syntax/token_stream.rs

@@ -14,7 +14,7 @@ impl<'s> TokenStream<'s> {
     pub fn new(filename: &str, s: &'s str) -> TokenStream<'s> {
         TokenStream {
             filename: InternedString::new(filename),
-            lexer: Token::lexer(s).spanned()
+            lexer: Token::lexer(s).spanned(),
         }
     }
 
@@ -28,7 +28,7 @@ impl<'s> TokenStream<'s> {
 #[derive(Clone, Debug, PartialEq)]
 pub enum Location {
     InFile(InternedString, usize),
-    Manufactured
+    Manufactured,
 }
 
 impl Location {
@@ -46,13 +46,13 @@ impl Default for Location {
 #[derive(Debug, PartialEq)]
 pub struct LexerError {
     filename: InternedString,
-    offset: usize
+    offset: usize,
 }
 
 #[cfg(test)]
 impl LexerError {
     fn new(filename: InternedString, offset: usize) -> LexerError {
-        LexerError{ filename, offset, }
+        LexerError { filename, offset }
     }
 }
 
@@ -64,12 +64,10 @@ impl<'s> Iterator for TokenStream<'s> {
     fn next(&mut self) -> Option<Self::Item> {
         match self.lexer.next() {
             None => None,
-            Some((Token::Error, span)) => {
+            Some((Token::Error, span)) => Some(Err(LexerError {
-                Some(Err(LexerError {
                 filename: self.filename,
                 offset: span.start,
-                }))
+            })),
-            }
             Some((token, span)) => {
                 let start = Location::new(self.filename, span.start);
                 let end = Location::new(self.filename, span.end);
@@ -83,11 +81,46 @@ impl<'s> Iterator for TokenStream<'s> {
 fn stream_works() {
     let fname = InternedString::new("<file>");
     let mut lex0 = TokenStream::new("<file>", "y = x + 1//foo");
-    assert_eq!(lex0.next(), Some(Ok((Location::new(fname, 0), Token::var("y"), Location::new(fname, 1)))));
+    assert_eq!(
-    assert_eq!(lex0.next(), Some(Ok((Location::new(fname, 2), Token::Equals, Location::new(fname, 3)))));
+        lex0.next(),
-    assert_eq!(lex0.next(), Some(Ok((Location::new(fname, 4), Token::var("x"), Location::new(fname, 5)))));
+        Some(Ok((
-    assert_eq!(lex0.next(), Some(Ok((Location::new(fname, 6), Token::Operator('+'), Location::new(fname, 7)))));
+            Location::new(fname, 0),
-    assert_eq!(lex0.next(), Some(Ok((Location::new(fname, 8), Token::Number((None, 1)), Location::new(fname, 9)))));
+            Token::var("y"),
+            Location::new(fname, 1)
+        )))
+    );
+    assert_eq!(
+        lex0.next(),
+        Some(Ok((
+            Location::new(fname, 2),
+            Token::Equals,
+            Location::new(fname, 3)
+        )))
+    );
+    assert_eq!(
+        lex0.next(),
+        Some(Ok((
+            Location::new(fname, 4),
+            Token::var("x"),
+            Location::new(fname, 5)
+        )))
+    );
+    assert_eq!(
+        lex0.next(),
+        Some(Ok((
+            Location::new(fname, 6),
+            Token::Operator('+'),
+            Location::new(fname, 7)
+        )))
+    );
+    assert_eq!(
+        lex0.next(),
+        Some(Ok((
+            Location::new(fname, 8),
+            Token::Number((None, 1)),
+            Location::new(fname, 9)
+        )))
+    );
     assert_eq!(lex0.next(), None);
 }
 

src/syntax/tokens.rs

@@ -6,7 +6,6 @@ use std::num::ParseIntError;
 pub enum Token {
     #[regex(r"[ \t\n\f]+", logos::skip)]
     #[regex(r"//.*", logos::skip)]
-
     #[token("=")]
     Equals,
 
@@ -37,7 +36,10 @@ impl Token {
     }
 }
 
-fn parse_number<'a,'src>(base: Option<u8>, value: &'a Lexer<'src, Token>) -> Result<(Option<u8>, i128), ParseIntError> {
+fn parse_number<'a, 'src>(
+    base: Option<u8>,
+    value: &'a Lexer<'src, Token>,
+) -> Result<(Option<u8>, i128), ParseIntError> {
     let (radix, strval) = match base {
         None => (10, value.slice()),
         Some(radix) => (radix, &value.slice()[2..]),
@@ -80,4 +82,3 @@ fn lexer_spans() {
     assert_eq!(lex0.next(), Some((Token::Number((None, 1)), 8..9)));
     assert_eq!(lex0.next(), None);
 }
-

src/util/istring.rs

@@ -1,5 +1,5 @@
 use lazy_static::lazy_static;
-use std::cmp::{Ordering, max};
+use std::cmp::{max, Ordering};
 use std::collections::HashMap;
 use std::fmt;
 use std::sync::RwLock;
@@ -22,16 +22,14 @@ impl InternedString {
 
         for (k, v) in table.iter() {
             if v == s {
-                return InternedString{ index: *k }
+                return InternedString { index: *k };
             }
             biggest_index = max(biggest_index, *k);
         }
 
         let res = biggest_index + 1;
         table.insert(res, s.to_string());
-        InternedString {
+        InternedString { index: res }
-            index: res
-        }
     }
 }