From 44cebec81881b71ef3c5f6fffe78ab9f7eb10092 Mon Sep 17 00:00:00 2001
From: Greg Shuflin <greg.shuflin@protonmail.com>
Date: Thu, 18 Nov 2021 22:12:13 -0800
Subject: [PATCH] For expr

---
 schala-lang/src/parsing/combinator.rs | 36 +++++++++++++++++++++++++++
 schala-lang/src/parsing/test.rs       |  4 +--
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/schala-lang/src/parsing/combinator.rs b/schala-lang/src/parsing/combinator.rs
index 1d031f9..ba910e5 100644
--- a/schala-lang/src/parsing/combinator.rs
+++ b/schala-lang/src/parsing/combinator.rs
@@ -448,6 +448,7 @@ fn primary_expr_no_struct(input: Span) -> ParseResult<ExpressionKind> {
         "primary-expr-no-struct",
         alt((
             while_expr,
+            for_expr,
             list_expr,
             paren_expr,
             string_literal,
@@ -481,6 +482,41 @@ fn while_expr(input: Span) -> ParseResult<ExpressionKind> {
     })(input)
 }
 
+fn for_expr(input: Span) -> ParseResult<ExpressionKind> {
+    println!("IN FOR EXPR: {}", input.fragment());
+    fn for_enumerators(input: Span) -> ParseResult<Vec<Enumerator>> {
+        println!("NEUMS: {}", input.fragment());
+        alt((
+            delimited(tok(char('{')), separated_list0(tok(char(',')), enumerator), tok(char('}'))),
+            map(enumerator, |enumerator| vec![enumerator]),
+        ))(input)
+    }
+
+    //TODO add guards, etc.
+    fn enumerator(input: Span) -> ParseResult<Enumerator> {
+        alt((
+            map(separated_pair(tok(identifier), kw("<-"), expression_no_struct), |(ident, generator)| {
+                Enumerator { id: rc_string(ident.fragment()), generator }
+            }),
+            //TODO distinguish these two cases in AST
+            map(separated_pair(tok(identifier), kw("="), expression_no_struct), |(ident, generator)| {
+                Enumerator { id: rc_string(ident.fragment()), generator }
+            }),
+        ))(input)
+    }
+
+    fn for_body(input: Span) -> ParseResult<Box<ForBody>> {
+        alt((
+            preceded(kw("return"), map(expression_no_struct, |expr| Box::new(ForBody::MonadicReturn(expr)))),
+            map(block, |body| Box::new(ForBody::StatementBlock(body))),
+        ))(input)
+    }
+
+    map(preceded(kw("for"), pair(for_enumerators, for_body)), |(enumerators, body)| {
+        ExpressionKind::ForExpression { enumerators, body }
+    })(input)
+}
+
 fn paren_expr(input: Span) -> ParseResult<ExpressionKind> {
     delimited(
         tok(char('(')),
diff --git a/schala-lang/src/parsing/test.rs b/schala-lang/src/parsing/test.rs
index 03ec6dc..0d608eb 100644
--- a/schala-lang/src/parsing/test.rs
+++ b/schala-lang/src/parsing/test.rs
@@ -389,7 +389,7 @@ fn while_expression() {
 fn for_expression() {
     use ExpressionKind::*;
 
-    assert_expr!(
+    assert_expr_comb!(
         "for { a <- garodzny::maybeValue } return 1",
         expr(ForExpression {
             enumerators: vec![Enumerator { id: rc("a"), generator: expr(Value(qn!(garodzny, maybeValue))) }],
@@ -397,7 +397,7 @@ fn for_expression() {
         })
     );
 
-    assert_expr!(
+    assert_expr_comb!(
         "for n <- someRange { f(n) ; }",
         expr(ForExpression {
             enumerators: vec![Enumerator { id: rc("n"), generator: expr(Value(qn!(someRange))) }],