From 899a4df55e064bb3845d7b5bc443561ef35e3cb3 Mon Sep 17 00:00:00 2001
From: Greg Shuflin <greg.shuflin@protonmail.com>
Date: Mon, 25 Oct 2021 23:01:32 -0700
Subject: [PATCH] Literal patterns

---
 schala-lang/language/src/reduced_ir/mod.rs    | 29 ++++++++++++++++++-
 schala-lang/language/src/reduced_ir/types.rs  |  8 ++++-
 .../language/src/tree_walk_eval/mod.rs        | 15 ++++++----
 .../language/src/tree_walk_eval/test.rs       | 13 +++++++++
 4 files changed, 58 insertions(+), 7 deletions(-)

diff --git a/schala-lang/language/src/reduced_ir/mod.rs b/schala-lang/language/src/reduced_ir/mod.rs
index c46572f..a244c6b 100644
--- a/schala-lang/language/src/reduced_ir/mod.rs
+++ b/schala-lang/language/src/reduced_ir/mod.rs
@@ -289,8 +289,35 @@ impl<'a> Reducer<'a> {
 
 impl ast::Pattern {
     fn reduce(&self, symbol_table: &SymbolTable) -> Result<Pattern, PatternError> {
+        Ok(match self {
+            ast::Pattern::Ignored => {
+                unimplemented!()
+            },
+            ast::Pattern::TuplePattern(/*Vec<Pattern>*/..) => {
+                unimplemented!()
 
-        Ok(Pattern::Ignored)
+            },
+            ast::Pattern::Literal(lit) => Pattern::Literal(match lit {
+                ast::PatternLiteral::NumPattern { neg, num } =>  match (neg, num) {
+                    (false, ast::ExpressionKind::NatLiteral(n)) => Literal::Nat(*n),
+                    (false, ast::ExpressionKind::FloatLiteral(f)) => Literal::Float(*f),
+                    (true, ast::ExpressionKind::NatLiteral(n)) => Literal::Int(-(*n as i64)),
+                    (true, ast::ExpressionKind::FloatLiteral(f)) => Literal::Float(-f),
+                    (_, e) => return Err(format!("Internal error, unexpected pattern literal: {:?}", e).into())
+                },
+                ast::PatternLiteral::StringPattern(s) => Literal::StringLit(s.clone()),
+                ast::PatternLiteral::BoolPattern(b) => Literal::Bool(*b),
+            }),
+            ast::Pattern::TupleStruct(_name, _subpatterns) => {
+                unimplemented!()
+            },
+            ast::Pattern::Record(name, /*Vec<(Rc<String>, Pattern)>*/ _) => {
+                unimplemented!()
+            },
+            ast::Pattern::VarOrName(_name) => {
+                unimplemented!()
+            },
+        })
     }
 }
 
diff --git a/schala-lang/language/src/reduced_ir/types.rs b/schala-lang/language/src/reduced_ir/types.rs
index b384134..bf52baa 100644
--- a/schala-lang/language/src/reduced_ir/types.rs
+++ b/schala-lang/language/src/reduced_ir/types.rs
@@ -108,7 +108,7 @@ pub enum Lookup {
     Param(u8),
 }
 
-#[derive(Debug, Clone)]
+#[derive(Debug, Clone, PartialEq)]
 pub enum Literal {
     Nat(u64),
     Int(i64),
@@ -149,3 +149,9 @@ impl From<&str> for PatternError {
         Self { msg: s.to_string() }
     }
 }
+
+impl From<String> for PatternError {
+    fn from(msg: String) -> Self {
+        Self { msg }
+    }
+}
diff --git a/schala-lang/language/src/tree_walk_eval/mod.rs b/schala-lang/language/src/tree_walk_eval/mod.rs
index f3f7152..a41d5eb 100644
--- a/schala-lang/language/src/tree_walk_eval/mod.rs
+++ b/schala-lang/language/src/tree_walk_eval/mod.rs
@@ -277,12 +277,17 @@ impl<'a> State<'a> {
 
   fn case_match_expression(&mut self, cond: Expression, alternatives: Vec<Alternative>) -> EvalResult<Primitive> {
 
-      fn matches(cond: &Expression, matcher: &Pattern) -> bool {
-          
-
-
-          false
+      fn matches(scrut: &Primitive, pat: &Pattern) -> bool {
+          match pat {
+              Pattern::Ignored => true,
+              Pattern::Literal(pat_literal) => if let Primitive::Literal(scrut_literal) = scrut {
+                  pat_literal == scrut_literal
+              } else {
+                  false
+              },
+          }
       }
+      let cond = self.expression(cond)?;
 
       for alt in alternatives.into_iter() {
           if matches(&cond, &alt.pattern) {
diff --git a/schala-lang/language/src/tree_walk_eval/test.rs b/schala-lang/language/src/tree_walk_eval/test.rs
index 40a1646..9287920 100644
--- a/schala-lang/language/src/tree_walk_eval/test.rs
+++ b/schala-lang/language/src/tree_walk_eval/test.rs
@@ -85,6 +85,19 @@ fn basic_if_statement() {
     eval_assert(source, "69");
 }
 
+#[test]
+fn basic_patterns() {
+    let source =r#"
+let x = 10
+let a = if x is 10 then { 255 } else { 256 }
+let b = if 23 is 99 then { 255 } else { 256 }
+let c = if true is false then { 9 } else { 10 }
+let d = if "xxx" is "yyy" then { 20 } else { 30 }
+(a, b, c, d)
+    "#;
+    eval_assert(source, "(255, 256, 10, 30)");
+}
+
 #[test]
 fn if_is_patterns() {
   let source = r#"