From fa7b6ce96b1aa0cc57d01dfeb76c53d5d5e74132 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Tue, 21 Aug 2018 19:57:45 -0700
Subject: [PATCH] Handle negatives in patterns correctly

---
 schala-lang/src/ast.rs         |  5 +++-
 schala-lang/src/parsing.rs     | 55 ++++++++++++++++++++++++++++++----
 schala-lang/src/reduced_ast.rs |  4 +--
 3 files changed, 55 insertions(+), 9 deletions(-)

diff --git a/schala-lang/src/ast.rs b/schala-lang/src/ast.rs
index 17fe965..8832c04 100644
--- a/schala-lang/src/ast.rs
+++ b/schala-lang/src/ast.rs
@@ -157,7 +157,10 @@ pub enum Pattern {
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum PatternLiteral {
-  NumPattern(ExpressionType), //TODO fix
+  NumPattern {
+    neg: bool,
+    num: ExpressionType,
+  },
   StringPattern(Rc<String>),
   BoolPattern(bool),
   VarPattern(Rc<String>)
diff --git a/schala-lang/src/parsing.rs b/schala-lang/src/parsing.rs
index 505e530..8e7d125 100644
--- a/schala-lang/src/parsing.rs
+++ b/schala-lang/src/parsing.rs
@@ -235,7 +235,8 @@ digits := (DIGIT_GROUP underscore)+
 /* Pattern syntax */
 pattern := '(' (pattern, ',')* ')' | simple_pattern
 simple_pattern := pattern_literal | record_pattern | tuple_struct_pattern
-pattern_literal := 'true' | 'false' | number_literal | STR_LITERAL | IDENTIFIER
+pattern_literal := 'true' | 'false' | signed_number_literal | STR_LITERAL | IDENTIFIER
+signed_number_literal := '-'? number_literal
 record_pattern := IDENTIFIER '{' (record_pattern_entry, ',')* '}'
 record_pattern_entry := IDENTIFIER | IDENTIFIER ':' Pattern
 tuple_struct_pattern := IDENTIFIER '(' (pattern, ',')* ')'
@@ -735,14 +736,12 @@ impl Parser {
           _ => Pattern::Literal(PatternLiteral::VarPattern(id))
         }
       },
+      //TODO I think these are buggy b/c they don't advance the parser
       Keyword(Kw::True) => Pattern::Literal(PatternLiteral::BoolPattern(true)),
       Keyword(Kw::False) => Pattern::Literal(PatternLiteral::BoolPattern(false)),
       StrLiteral(s) =>  Pattern::Literal(PatternLiteral::StringPattern(s)),
-      DigitGroup(_) | HexLiteral(_) | BinNumberSigil | Period => {
-        //TODO handle negatives
-        let Expression(expr_type, _) = self.number_literal()?;
-        Pattern::Literal(PatternLiteral::NumPattern(expr_type))
-      },
+      DigitGroup(_) | HexLiteral(_) | BinNumberSigil | Period => self.signed_number_literal()?,
+      Operator(ref op) if **op == "-" => self.signed_number_literal()?,
       Underscore => {
         self.next();
         Pattern::Ignored
@@ -751,6 +750,18 @@ impl Parser {
     })
   });
 
+  parse_method!(signed_number_literal(&mut self) -> ParseResult<Pattern> {
+    let neg = match self.peek() {
+      Operator(ref op) if **op == "-" => {
+        self.next();
+        true
+      },
+      _ => false
+    };
+    let Expression(expr_type, _) = self.number_literal()?;
+    Ok(Pattern::Literal(PatternLiteral::NumPattern { neg, num: expr_type }))
+  });
+
   parse_method!(record_pattern_entry(&mut self) -> ParseResult<(Rc<String>, Pattern)> {
     let name = self.identifier()?;
     Ok(match self.peek() {
@@ -1439,5 +1450,37 @@ fn a(x) {
           )
       ])
     }
+
+    parse_test! {
+      "if x is -1 then 1 else 2", AST(vec![
+        exprstatement!(
+          IfExpression {
+            discriminator: bx!(Discriminator::Simple(ex!(Value(rc!(x))))),
+            body: bx!(IfExpressionBody::SimplePatternMatch(
+              Pattern::Literal(PatternLiteral::NumPattern { neg: true, num: NatLiteral(1) }),
+              vec![exprstatement!(NatLiteral(1))],
+              Some(vec![exprstatement!(NatLiteral(2))]),
+            ))
+          }
+        )
+      ])
+    }
+
+    parse_test! {
+      "if x is 1 then 1 else 2", AST(vec![
+        exprstatement!(
+          IfExpression {
+            discriminator: bx!(Discriminator::Simple(ex!(Value(rc!(x))))),
+            body: bx!(IfExpressionBody::SimplePatternMatch(
+              Pattern::Literal(PatternLiteral::NumPattern { neg: false, num: NatLiteral(1) }),
+              vec![exprstatement!(NatLiteral(1))],
+              Some(vec![exprstatement!(NatLiteral(2))]),
+            ))
+          }
+        )
+      ])
+    }
+
+
   }
 }
diff --git a/schala-lang/src/reduced_ast.rs b/schala-lang/src/reduced_ast.rs
index 54999e6..346447d 100644
--- a/schala-lang/src/reduced_ast.rs
+++ b/schala-lang/src/reduced_ast.rs
@@ -173,7 +173,7 @@ fn reduce_if_expression(discriminator: &Discriminator, body: &IfExpressionBody,
             item: then_clause,
           }
         },
-        _ => panic!()
+        e => { println!("SAW {:?}", e); panic!() }
       };
 
       let alternatives = vec![
@@ -196,7 +196,7 @@ fn reduce_if_expression(discriminator: &Discriminator, body: &IfExpressionBody,
           Guard::Pat(ref p) => match p {
             Pattern::Ignored => (None, vec![]),
             Pattern::Literal(lit) => match lit {
-              PatternLiteral::NumPattern(_expr) => unimplemented!(),
+              PatternLiteral::NumPattern { neg, num } => unimplemented!(),
               PatternLiteral::StringPattern(_s) => unimplemented!(),
               PatternLiteral::BoolPattern(_b) => unimplemented!(),
               PatternLiteral::VarPattern(_var) => unimplemented!(),