From ad76f41b527318a558fa90ac56b3fde57daa8b8c Mon Sep 17 00:00:00 2001
From: Scott Richmond <kredati@users.noreply.github.com>
Date: Thu, 21 Nov 2024 22:36:57 -0500
Subject: [PATCH] parse docstrings

---
 src/main.rs   |  9 +++++++--
 src/parser.rs | 43 ++++++++++++++++++++++++++-----------------
 src/vm.rs     |  2 +-
 3 files changed, 34 insertions(+), 20 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index f6c1e6d..5a48bae 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -30,7 +30,7 @@
 //     * [x] `loop` and `recur`
 //     * [ ] string patterns
 //     * [ ] string interpolation
-//     * [ ] docstrings
+//     * [x] docstrings
 // * [~] write `base` in Rust
 // * [ ] turn this into a library function
 // * [ ] compile this into WASM
@@ -58,7 +58,12 @@ use crate::base::*;
 
 pub fn main() {
     let src = "
-true
+fn foo {
+    \"this is a docstring\"
+    () -> :foo
+    (_) -> :bar
+}
+foo ()
     ";
     let (tokens, lex_errs) = lexer().parse(src).into_output_errors();
     if !lex_errs.is_empty() {
diff --git a/src/parser.rs b/src/parser.rs
index b064a77..6d1cd8a 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -54,7 +54,7 @@ pub enum Ast<'src> {
     Synthetic(Box<Spanned<Self>>, Box<Spanned<Self>>, Vec<Spanned<Self>>),
     When(Vec<Spanned<WhenClause<'src>>>),
     Match(Box<Spanned<Self>>, Vec<MatchClause<'src>>),
-    Fn(&'src str, Vec<MatchClause<'src>>),
+    Fn(&'src str, Vec<MatchClause<'src>>, Option<&'src str>),
     FnDeclaration(&'src str),
     Panic(Box<Spanned<Self>>),
     Do(Vec<Spanned<Self>>),
@@ -149,7 +149,7 @@ impl fmt::Display for Ast<'_> {
                         .join("\n")
                 )
             }
-            Ast::Fn(name, clauses) => {
+            Ast::Fn(name, clauses, _) => {
                 write!(
                     f,
                     "fn: {}\n{}",
@@ -407,10 +407,11 @@ where
         Token::Nil => Ast::Nil,
         Token::Boolean(b) => Ast::Boolean(b),
         Token::Number(n) => Ast::Number(n),
-        Token::String(s) => Ast::String(s),
     }
     .map_with(|v, e| (v, e.span()));
 
+    let string = select! {Token::String(s) => Ast::String(s)}.map_with(|s, e| (s, e.span()));
+
     let tuple = simple
         .clone()
         .separated_by(separators.clone())
@@ -505,6 +506,7 @@ where
             .or(tuple.clone())
             .or(list)
             .or(dict)
+            .or(string)
             .labelled("simple expression"),
     );
 
@@ -599,12 +601,6 @@ where
 
     let conditional = when.or(if_).or(match_);
 
-    //todo:
-    // * [x] do
-    // * [ ] loop
-    // * [x] repeat
-    // * [x] panic!
-
     let panic = just(Token::Reserved("panic!"))
         .ignore_then(nonbinding.clone())
         .map_with(|expr, e| (Ast::Panic(Box::new(expr)), e.span()));
@@ -653,14 +649,17 @@ where
 
     let lambda = just(Token::Reserved("fn"))
         .ignore_then(fn_unguarded.clone())
-        .map_with(|clause, e| (Ast::Fn("anonymous", vec![clause]), e.span()));
+        .map_with(|clause, e| (Ast::Fn("anonymous", vec![clause], None), e.span()));
 
-    let fn_multiclause = fn_clause
+    let fn_clauses = fn_clause
         .clone()
         .separated_by(terminators.clone())
         .allow_leading()
         .allow_trailing()
-        .collect()
+        .collect();
+
+    let loop_multiclause = fn_clauses
+        .clone()
         .delimited_by(just(Token::Punctuation("{")), just(Token::Punctuation("}")));
 
     let fn_single_clause = fn_clause.clone().map_with(|c, _| vec![c]);
@@ -668,7 +667,7 @@ where
     let r#loop = just(Token::Reserved("loop"))
         .ignore_then(tuple.clone())
         .then_ignore(just(Token::Reserved("with")))
-        .then(fn_multiclause.clone().or(fn_single_clause.clone()))
+        .then(loop_multiclause.clone().or(fn_single_clause.clone()))
         .map_with(|(init, body), e| (Ast::Loop(Box::new(init), body), e.span()));
 
     nonbinding.define(
@@ -725,19 +724,29 @@ where
             } else {
                 unreachable!()
             };
-            (Ast::Fn(name, vec![clause]), e.span())
+            (Ast::Fn(name, vec![clause], None), e.span())
         });
 
+    let docstr = select! {Token::String(s) => s};
+
+    let fn_multiclause = separators
+        .clone()
+        .or_not()
+        .ignore_then(docstr.or_not())
+        .then(fn_clauses.clone())
+        .delimited_by(just(Token::Punctuation("{")), just(Token::Punctuation("}")))
+        .map_with(|(docstr, clauses), e| (docstr, clauses, e.span()));
+
     let fn_compound = just(Token::Reserved("fn"))
         .ignore_then(word)
-        .then(fn_multiclause.clone())
-        .map_with(|(word, clauses), e| {
+        .then(fn_multiclause)
+        .map_with(|(word, (docstr, clauses, _)), e| {
             let name = if let Ast::Word(word) = word.0 {
                 word
             } else {
                 unreachable!()
             };
-            (Ast::Fn(name, clauses), e.span())
+            (Ast::Fn(name, clauses, docstr), e.span())
         });
 
     let fn_ = fn_named.or(fn_compound).or(fn_decl);
diff --git a/src/vm.rs b/src/vm.rs
index f2073c7..df08f28 100644
--- a/src/vm.rs
+++ b/src/vm.rs
@@ -414,7 +414,7 @@ pub fn eval<'src, 'a>(
             let value = eval(&value.0, ctx)?;
             match_clauses(&value, clauses, ctx)
         }
-        Ast::Fn(name, clauses) => {
+        Ast::Fn(name, clauses, ..) => {
             let the_fn = Value::Fn::<'src>(Rc::new(Fn::<'src> {
                 name,
                 body: clauses,