From c713c36d7c86cb435181500cda3d376aace6a986 Mon Sep 17 00:00:00 2001
From: Stephen D <webmaster@scd31.com>
Date: Tue, 11 Mar 2025 12:55:21 -0400
Subject: [PATCH] parsing works???
---
src/expr.rs | 20 +++++++-
src/flatten.rs | 2 +-
src/main.rs | 18 ++++---
src/parser.rs | 125 +++++++++++++++++++++++++++++++------------------
src/scanner.rs | 3 ++
src/stmt.rs | 6 +++
src/token.rs | 2 +
7 files changed, 120 insertions(+), 56 deletions(-)
create mode 100644 src/stmt.rs
diff --git a/src/expr.rs b/src/expr.rs
index 42eef34..eed7c65 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -1,3 +1,5 @@
+use std::fmt::Display;
+
use bitvec::{order::Msb0, vec::BitVec};
#[derive(Debug)]
@@ -16,7 +18,7 @@ pub enum FlattenedExpr {
}
impl FlattenedExpr {
- pub fn to_blc(self, bv: &mut BitVec<u8, Msb0>) {
+ pub fn to_blc(&self, bv: &mut BitVec<u8, Msb0>) {
match self {
FlattenedExpr::Abs(expr) => {
bv.push(false);
@@ -32,7 +34,7 @@ impl FlattenedExpr {
right.to_blc(bv);
}
FlattenedExpr::Var(x) => {
- for _ in 0..=x {
+ for _ in 0..=*x {
bv.push(true);
}
@@ -41,3 +43,17 @@ impl FlattenedExpr {
}
}
}
+
+impl Display for FlattenedExpr {
+ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ match self {
+ FlattenedExpr::Abs(expr) => {
+ write!(f, "λ{}", expr)?;
+ }
+ FlattenedExpr::App(left, right) => write!(f, "[{} {}]", left, right)?,
+ FlattenedExpr::Var(var) => write!(f, "{var}")?,
+ }
+
+ Ok(())
+ }
+}
diff --git a/src/flatten.rs b/src/flatten.rs
index 53e5432..7d51539 100644
--- a/src/flatten.rs
+++ b/src/flatten.rs
@@ -12,7 +12,7 @@ impl Flattener {
}
pub fn flatten(&mut self, main: &Expr) -> Option<FlattenedExpr> {
- self.flatten_expr(&main, HashSet::new())
+ self.flatten_expr(main, HashSet::new())
}
fn flatten_expr<'a>(
diff --git a/src/main.rs b/src/main.rs
index 45cec78..bc62b3c 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,17 +7,21 @@ mod expr;
mod flatten;
mod parser;
mod scanner;
+mod stmt;
mod token;
fn main() {
let scanner = Scanner::new(
"
-$false=λtf.f
-$omega=λa. (a a)
+ $false=λtf.f;
+ $omega=λa. (a a);
-λa.a($omega(λbcde.d(bb)(λf.fce)))$false
-",
+ (λa.a($omega(λbcde.d(bb)(λf.fce)))$false);
+ #(λabc.cb(ab));
+ #(λabc.cba);
+ ",
+ // "((λab.ba)(λa.a))",
);
let tokens = scanner.scan_tokens().unwrap();
@@ -28,12 +32,12 @@ $omega=λa. (a a)
let mut flattener = Flattener::new(funcs);
let flat = flattener.flatten(&main).unwrap();
- dbg!(&flat);
+ println!("{flat}");
- let mut bv = BitVec::new();
+ /*let mut bv = BitVec::new();
flat.to_blc(&mut bv);
for x in bv.as_raw_slice() {
print!("{}", *x as char);
- }
+ }*/
}
diff --git a/src/parser.rs b/src/parser.rs
index 576b45f..035258c 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -2,6 +2,7 @@ use std::collections::HashMap;
use crate::{
expr::Expr,
+ stmt::Stmt,
token::{Token, TokenType},
};
@@ -24,36 +25,14 @@ impl Parser {
let mut definitions = HashMap::new();
let mut main_expr = None;
while !self.is_at_end() {
- let t = self.peek().token_type.clone();
+ let stmt = self.stmt()?;
- match t {
- TokenType::DefinitionName(name) => {
- self.advance(); // consume definition name
-
- // function expr
-
- if self.peek().token_type != TokenType::Equals {
- self.print_error("Expected '=' after definition name");
-
- return None;
- }
-
- self.advance(); // consume equals
-
- let definition = self.expr()?;
-
- if definitions.contains_key(&name) {
- self.print_error(&format!("Duplicate definition for ${}", name));
- return None;
- }
-
- definitions.insert(name, definition);
+ match stmt {
+ Stmt::Definition(name, expr) => {
+ definitions.insert(name, expr);
}
- // main expr
- _ => {
- let expr = self.expr()?;
-
+ Stmt::Main(expr) => {
if main_expr.is_some() {
self.print_error("Duplicate primary expression");
return None;
@@ -74,7 +53,51 @@ impl Parser {
}
}
+ fn stmt(&mut self) -> Option<Stmt> {
+ let stmt = if *self.peek_next() == TokenType::Equals {
+ // definition
+ let TokenType::DefinitionName(name) = &self.advance().token_type else {
+ self.print_error("Expected definition name before '='");
+ return None;
+ };
+
+ let name = name.clone();
+
+ // consume =
+ self.advance();
+
+ let expr = self.expr()?;
+
+ Stmt::Definition(name, expr)
+ } else {
+ Stmt::Main(self.expr()?)
+ };
+
+ // consume semicolon
+ if self.peek().token_type != TokenType::Semicolon {
+ self.print_error("Expected ';' after statement");
+ return None;
+ }
+
+ self.advance();
+
+ Some(stmt)
+ }
+
fn expr(&mut self) -> Option<Expr> {
+ let mut expr = self.expr_once()?;
+
+ dbg!(&expr);
+
+ while !self.is_at_end_of_expr() {
+ let right = self.expr_once()?;
+ expr = Expr::App(Box::new(expr), Box::new(right));
+ }
+
+ Some(expr)
+ }
+
+ fn expr_once(&mut self) -> Option<Expr> {
match &self.peek().token_type {
TokenType::Lambda => self.abstraction(),
@@ -85,7 +108,22 @@ impl Parser {
Some(Expr::DefinitionName(name))
}
- TokenType::LeftParen => self.application(),
+ TokenType::LeftParen => {
+ self.advance(); // consume (
+
+ let expr = self.expr()?;
+
+ dbg!(&self.peek().token_type);
+
+ if self.peek().token_type != TokenType::RightParen {
+ self.print_error("Expected ')'");
+ return None;
+ }
+
+ self.advance(); // consume )
+
+ Some(expr)
+ }
TokenType::Variable(c) => {
let c = *c;
@@ -95,6 +133,8 @@ impl Parser {
}
_ => {
+ dbg!(&self.peek().token_type);
+
self.print_error(
"Unexpected token. Expected one of 'λ', '/', '\\', '$', '(', or a variable",
);
@@ -128,23 +168,9 @@ impl Parser {
Some(expr)
}
- fn application(&mut self) -> Option<Expr> {
- self.advance(); // consume left paren
-
- let left = self.expr()?;
- let right = self.expr()?;
-
- if self.peek().token_type != TokenType::RightParen {
- self.print_error("Expected ')' after application");
- return None;
- }
-
- self.advance(); // consume right paren
-
- Some(Expr::App(Box::new(left), Box::new(right)))
- }
-
fn find_variable(&self, name: char) -> Option<usize> {
+ dbg!(name, &self.env);
+
let ret = self
.env
.iter()
@@ -153,7 +179,7 @@ impl Parser {
.map(|(i, _)| i);
match ret {
- Some(x) => Some(x),
+ Some(x) => Some(self.env.len() - x - 1),
None => {
self.print_error(&format!("Unknown variable '{}'.", name));
@@ -182,7 +208,14 @@ impl Parser {
}
fn is_at_end(&self) -> bool {
- self.tokens.len() == self.current
+ self.peek().token_type == TokenType::Eof
+ }
+
+ fn is_at_end_of_expr(&self) -> bool {
+ let tt = &self.peek().token_type;
+
+ // end of expr can be ), $, or end of file
+ matches!(tt, TokenType::RightParen | TokenType::Semicolon)
}
fn print_error(&self, err: &str) {
diff --git a/src/scanner.rs b/src/scanner.rs
index 20fc7b3..94a5581 100644
--- a/src/scanner.rs
+++ b/src/scanner.rs
@@ -26,6 +26,8 @@ impl Scanner {
self.scan_token()?;
}
+ self.add_token(TokenType::Eof);
+
Ok(self.tokens)
}
@@ -38,6 +40,7 @@ impl Scanner {
')' => RightParen,
'.' => Period,
'=' => Equals,
+ ';' => Semicolon,
' ' | '\r' | '\n' | '\t' => NoToken,
'\\' | '/' | 'λ' => Lambda,
_ if c.is_alphabetic() => Variable(c),
diff --git a/src/stmt.rs b/src/stmt.rs
new file mode 100644
index 0000000..609f829
--- /dev/null
+++ b/src/stmt.rs
@@ -0,0 +1,6 @@
+use crate::expr::Expr;
+
+pub enum Stmt {
+ Main(Expr),
+ Definition(String, Expr),
+}
diff --git a/src/token.rs b/src/token.rs
index 8e2cd83..9f51ce2 100644
--- a/src/token.rs
+++ b/src/token.rs
@@ -6,10 +6,12 @@ pub enum TokenType {
Period,
Equals,
+ Semicolon,
LeftParen,
RightParen,
+ Eof,
NoToken,
}
--
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