start to reimplement matzo in rust

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Cargo.toml

@@ -0,0 +1,30 @@
+[package]
+name = "matzo"
+version = "0.1.0"
+edition = "2021"
+default-run = "matzo"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[lib]
+name = "matzo"
+
+[[bin]]
+name = "matzo"
+path = "src/main.rs"
+
+[[bin]]
+name = "matzo-regenerate"
+test = true
+path = "tools/regenerate.rs"
+
+[dependencies]
+regex = "1"
+lalrpop-util = { version = "*", features = ["lexer"] }
+
+[build-dependencies.lalrpop]
+version = "*"
+features = ["lexer"]
+
+[dev-dependencies]
+pretty_assertions = "*"

build.rs

@@ -0,0 +1,67 @@
+use std::env;
+use std::fs::File;
+use std::io::Write;
+use std::path::Path;
+
+const TEST_PREFIX: &str = "
+#[cfg(test)]
+use pretty_assertions::assert_eq;
+use crate::grammar;
+use std::io::Write;
+
+// to let us use pretty_assertions with strings, we write a newtype
+// that delegates Debug to Display
+#[derive(PartialEq, Eq)]
+struct StringWrapper<'a> {
+  wrapped: &'a str,
+}
+
+impl<'a> core::fmt::Debug for StringWrapper<'a> {
+  fn fmt(&self, f: &mut core::fmt::Formatter) -> core::fmt::Result {
+    core::fmt::Display::fmt(self.wrapped, f)
+  }
+}
+
+fn assert_eq(x: &str, y: &str) {
+  assert_eq!(StringWrapper {wrapped: x}, StringWrapper {wrapped: y});
+}
+";
+
+const TEST_TEMPLATE: &str = "
+#[test]
+fn test_%PREFIX%() {
+  let source = include_str!(\"%ROOT%/tests/%PREFIX%.matzo\");
+  let ast = grammar::StmtsParser::new().parse(source);
+  assert!(ast.is_ok());
+  let ast = ast.unwrap();
+
+  let mut buf = Vec::new();
+  writeln!(buf, \"{:#?}\", ast).unwrap();
+  assert_eq(
+    std::str::from_utf8(&buf).unwrap().trim(),
+    include_str!(\"%ROOT%/tests/%PREFIX%.parsed\").trim(),
+  );
+}
+";
+
+fn main() {
+    lalrpop::process_root().unwrap();
+
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let manifest_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
+    let dest = Path::new(&out_dir).join("exp_tests.rs");
+    let mut test_file = File::create(&dest).unwrap();
+    writeln!(test_file, "{}", TEST_PREFIX).unwrap();
+
+    for exp in std::fs::read_dir("tests").unwrap() {
+        let exp = exp.unwrap().path().canonicalize().unwrap();
+        let fname = exp.file_name().unwrap().to_string_lossy();
+        if let Some(prefix) = fname.strip_suffix(".matzo") {
+            let test = TEST_TEMPLATE
+                .replace("%FILE%", &fname)
+                .replace("%PREFIX%", prefix)
+                .replace("%ROOT%", &manifest_dir);
+            writeln!(test_file, "{}", test).unwrap();
+        }
+    }
+}

src/ast.rs

@@ -0,0 +1,49 @@
+type Name = String;
+
+#[derive(Debug)]
+pub enum Stmt {
+    Puts(Expr),
+    Fix(Name),
+    Assn(Name, Expr),
+    LitAssn(Name, Vec<String>),
+}
+
+#[derive(Debug)]
+pub enum Expr {
+    Var(Name),
+    Cat(Vec<Expr>),
+    Chc(Vec<Choice>),
+    Rep(i64, Box<Expr>),
+    Lit(Literal),
+    Ap(Box<Expr>, Box<Expr>),
+    Tup(Vec<Expr>),
+    Let(Name, Box<Expr>, Box<Expr>),
+    Fun(Vec<Case>),
+    Case(Box<Expr>, Vec<Case>),
+}
+
+#[derive(Debug)]
+pub struct Case {
+    pub pat: Pat,
+    pub expr: Expr,
+}
+
+#[derive(Debug)]
+pub enum Pat {
+    Var(Name),
+    Lit(Literal),
+    Tup(Vec<Pat>),
+}
+
+#[derive(Debug)]
+pub struct Choice {
+    pub weight: Option<i64>,
+    pub value: Expr,
+}
+
+#[derive(Debug)]
+pub enum Literal {
+    Str(String),
+    Atom(String),
+    Num(i64),
+}

src/grammar.lalrpop

@@ -0,0 +1,62 @@
+use std::str::FromStr;
+
+grammar;
+
+match {
+    "<",
+    ">",
+    "|",
+    ":",
+    ",",
+    ";",
+    ":=",
+    "::=",
+    "puts",
+    "case",
+    "let",
+    "in",
+    r"[a-z][A-Za-z0-9_-]*",
+    r"[A-Z][A-Za-z0-9_-]*",
+    r"[0-9]+",
+}
+
+use crate::ast::*;
+
+pub Stmts: Vec<Stmt> = {
+  <mut stmts:(<Stmt> ";")*> <stmt:Stmt?> => match stmt {
+    None => stmts,
+    Some(stmt) => {
+      stmts.push(stmt);
+      stmts
+    }
+  },
+};
+
+pub Stmt: Stmt = {
+  "puts" <Expr> => Stmt::Puts(<>),
+  <Name> ":=" <Expr> => Stmt::Assn(<>),
+};
+
+pub Name: String = {
+  r"[a-z][A-Za-z0-9_-]*" => <>.to_owned(),
+};
+
+pub Expr: Expr = {
+  <Literal> => Expr::Lit(<>),
+  <Name> => Expr::Var(<>),
+  "<" <mut es:(<Expr> ",")*> <e:Expr> ">" => {
+    es.push(e);
+    Expr::Tup(es)
+  },
+  "let" <name:Name> ":=" <e1:Expr> "in" <e2:Expr> =>
+    Expr::Let(name, Box::new(e1), Box::new(e2)),
+};
+
+pub Num: i64 = {
+  r"[0-9]+" => i64::from_str(<>).unwrap(),
+};
+
+pub Literal: Literal = {
+  <Num> => Literal::Num(<>),
+  r"[A-Z][A-Za-z0-9_-]*" => Literal::Atom(<>.to_owned()),
+};

src/lib.rs

@@ -0,0 +1,12 @@
+#[macro_use]
+extern crate lalrpop_util;
+
+pub mod ast;
+
+#[cfg(test)]
+pub mod test {
+    include!(concat!(env!("OUT_DIR"), "/exp_tests.rs"));
+}
+
+
+lalrpop_mod!(#[allow(clippy::all)] pub grammar);

src/main.rs

@@ -0,0 +1,3 @@
+fn main() {
+    println!("{:?}", matzo::grammar::StmtsParser::new().parse("puts 55"));
+}

tests/num_lit.matzo

@@ -0,0 +1 @@
+puts 55;

tests/num_lit.parsed

@@ -0,0 +1,9 @@
+[
+    Puts(
+        Lit(
+            Num(
+                55,
+            ),
+        ),
+    ),
+]

tools/regenerate.rs

@@ -0,0 +1,27 @@
+use matzo::grammar;
+
+use std::io::Write;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    for exp in std::fs::read_dir("tests")? {
+        let exp = exp?.path().canonicalize()?;
+        let fname = exp.file_name().ok_or("bad")?.to_string_lossy();
+        if let Some(prefix) = fname.strip_suffix(".matzo") {
+            println!("regenerating {}.matzo", prefix);
+            let exp_filename = |new_suffix| {
+                let mut f = exp.clone();
+                f.pop();
+                f.push(format!("{}.{}", prefix, new_suffix));
+                f
+            };
+
+            let src = std::fs::read_to_string(&exp)?;
+            if let Ok(ast) = grammar::StmtsParser::new().parse(&src) {
+                let mut f = std::fs::File::create(exp_filename("parsed"))?;
+                writeln!(f, "{:#?}", ast)?;
+            }
+        }
+    }
+
+    Ok(())
+}