From eabfc31bfbb7ce761909c7815a087b5fc10bfc99 Mon Sep 17 00:00:00 2001
From: Per Lindgren <per.lindgren@ltu.se>
Date: Tue, 15 Sep 2020 00:22:45 +0200
Subject: [PATCH] epic fail
---
src/ast/ast.rs | 26 --------
src/ast/main.rs | 137 ++---------------------------------------
src/ast/parser.lalrpop | 39 ++++++++++--
3 files changed, 40 insertions(+), 162 deletions(-)
diff --git a/src/ast/ast.rs b/src/ast/ast.rs
index 9daa62a..b750a43 100644
--- a/src/ast/ast.rs
+++ b/src/ast/ast.rs
@@ -3,29 +3,3 @@ use std::fmt;
// ast
pub type Id = String;
-
-// println!("{:?}", ..)
-#[derive(Debug, Clone)]
-pub enum NumOrId {
- Num(i32),
- Id(Id),
-}
-
-// println!("{}", ..)
-impl fmt::Display for NumOrId {
- fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
- match self {
- NumOrId::Num(i) => write!(f, "{}", i)?,
- NumOrId::Id(s) => write!(f, "{}", s)?,
- };
- Ok(())
- }
-}
-
-pub type Stmts = Vec<Stmt>;
-
-#[derive(Debug, Clone)]
-pub enum Stmt {
- Let(Id, NumOrId),
- If(Id, Stmts, Option<Stmts>),
-}
diff --git a/src/ast/main.rs b/src/ast/main.rs
index 08deadd..0eb05e3 100644
--- a/src/ast/main.rs
+++ b/src/ast/main.rs
@@ -8,137 +8,12 @@ pub mod ast;
use ast::*;
fn main() {
- println!("minimal");
- println!("{:?}", NumOrIdParser::new().parse("123"));
- println!("{:?}", NumOrIdParser::new().parse("a1_a"));
-
- println!("{}", NumOrIdParser::new().parse("123").unwrap());
- println!("{}", NumOrIdParser::new().parse("a1_a").unwrap());
-}
-
-#[test]
-fn parse_num_or_id() {
- assert_eq!(
- format!("{}", NumOrIdParser::new().parse("123").unwrap()),
- "123"
- );
- assert_eq!(
- format!("{}", NumOrIdParser::new().parse("a1_a").unwrap()),
- "a1_a"
- );
-}
-
-type Error = String;
-
-fn type_check(stmts: &Stmts) -> Result<Id, Error> {
- let mut last_id = "".to_string();
- let mut err: Option<Stmt> = None;
- stmts.iter().for_each(|stmt| match stmt {
- Stmt::Let(id, _) => {
- println!("let {} ...", id);
- last_id = id.to_string();
- }
- Stmt::If(_, _, __) => {
- println!("if has an error");
- err = Some(stmt.clone());
- }
- });
- println!("here we can do something before returning");
- match err {
- Some(stmt) => Err(format!("error found in statement {:?}", stmt)),
- None => Ok(last_id),
- }
-}
-// the above is not ideal, since we have to do a lot of book keeping,
-// also we cannot easily "abort", and thus we cont. even after spotting the error we want to return
-
-fn type_check2(stmts: &Stmts) -> Result<Id, Error> {
- let mut last_id = "".to_string();
- let res: Result<Id, Error> = stmts
- .iter()
- .try_for_each(|stmt| match stmt {
- Stmt::Let(id, _) => {
- println!("let {} ...", id);
- last_id = id.to_string();
- Ok(())
- }
- Stmt::If(_, _, __) => {
- println!("if has an error");
- Err(format!("error found in statement {:?}", stmt))
- }
- })
- .map(|_| Ok(last_id))?;
- println!("here we can do something before returning");
- res
-}
-// this is quite good, we can get rid of some book keeping, and we iterate only up to the point where an error occurs.
-// we have to convert the Ok(()) into the last Id (using Result::map)
-// IMHO Result::map should have been named map_ok, since that is what is does, and symmetric to map_err.
-
-fn type_check3(stmts: &Stmts) -> Result<Id, Error> {
- let res = stmts.iter().try_fold("".to_string(), |_, stmt| match stmt {
- Stmt::Let(id, _) => {
- println!("let {} ...", id);
- Ok(id.to_string())
- }
- Stmt::If(_, _, __) => {
- println!("if has an error");
- Err(format!("error found in statement {:?}", stmt))
+ let s = "
+ {
+ let ;
+ ;
}
- });
-
- println!("here we can do something before returning");
- res
-}
-// this is likely as good as it gets using Rust.
-// the `try_fold`, aborts on an error directly.
-// we need to give an initial value for the accumulator ("".to_string())
-// in this case we don't accumulate, so the first closure parameter is discarded (`_`)
-// instead we just overwrite the accumatore with the latest seen identifier.
-
-fn type_check4(stmts: &Stmts) -> Result<Id, Error> {
- let res = stmts
- .iter()
- .try_fold("".to_string(), |_, stmt| match stmt {
- Stmt::Let(id, _) => {
- println!("let {} ...", id);
- Ok(id.to_string())
- }
- Stmt::If(_, _, __) => {
- println!("if has an error");
- Err(format!("error found in statement {:?}", stmt))
- }
- })?;
-
- println!("here we can do something before returning");
- Ok(res)
-}
-// A slight alternation av type_check3, here we make an early return
-// Notice that the type of `res` has changed.
-
-#[test]
-fn test_stmts() {
- let stmts = vec![
- Stmt::Let("a".to_string(), NumOrId::Num(1)),
- Stmt::Let("b".to_string(), NumOrId::Num(2)),
- Stmt::If("b".to_string(), Stmts::new(), None),
- Stmt::Let("c".to_string(), NumOrId::Num(3)),
- ];
- println!("type_check {:?}", type_check(&stmts));
- println!("type_check2 {:?}", type_check2(&stmts));
- println!("type_check3 {:?}", type_check3(&stmts));
- println!("type_check4 {:?}", type_check4(&stmts));
-}
+ ";
-#[test]
-fn test_stmts_without_error() {
- let stmts = vec![
- Stmt::Let("a".to_string(), NumOrId::Num(1)),
- Stmt::Let("b".to_string(), NumOrId::Num(2)),
- Stmt::Let("c".to_string(), NumOrId::Num(3)),
- ];
- println!("type_check {:?}", type_check(&stmts));
- println!("type_check2 {:?}", type_check2(&stmts));
- println!("type_check3 {:?}", type_check3(&stmts));
- println!("type_check4 {:?}", type_check4(&stmts));
+ println!("{:?}", BlockExpressionParser::new().parse(s));
}
diff --git a/src/ast/parser.lalrpop b/src/ast/parser.lalrpop
index 3405c21..95085a6 100644
--- a/src/ast/parser.lalrpop
+++ b/src/ast/parser.lalrpop
@@ -4,15 +4,44 @@ use crate::ast::*;
grammar;
-pub NumOrId: NumOrId = {
- Num => NumOrId::Num(<>),
- Id => NumOrId::Id(<>),
+pub ExpressionWithoutBlock: () = {
+ LiteralExpression => ()
}
-
+
+pub LiteralExpression = {
+ Num
+ Id
+}
+
+ExpressionWithBlock: () = {
+ BlockExpression => ()
+}
+
+pub BlockExpression: ()= {
+ "{" Statements? "}" => ()
+}
+
+pub Statements: () = {
+ Statement+ => (),
+ Statement+ ExpressionWithoutBlock => (),
+ ExpressionWithBlock => ()
+}
+
+pub Statement: () = {
+ ";" => (),
+ "let" ";" => (),
+ ExpressionStatement => ()
+}
+
+pub ExpressionStatement: () = {
+ ExpressionWithoutBlock ";" => (),
+ ExpressionWithBlock ";"? => ()
+}
+
pub Num: i32 = {
r"[0-9]+" => i32::from_str(<>).unwrap(),
};
pub Id: String = {
r"([a-z]|[A-Z])([a-z]|[A-Z]|[0-9]|_)*" => String::from_str(<>).unwrap(),
-};
+};
\ No newline at end of file
--
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