From f4ff92302f180099eca6102830827039183b8246 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Tue, 30 Oct 2018 18:46:06 -0700
Subject: [PATCH] Use subpattern abstraction

---
 schala-lang/language/src/reduced_ast.rs | 27 +++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/schala-lang/language/src/reduced_ast.rs b/schala-lang/language/src/reduced_ast.rs
index f6e4d26..7fbd7a8 100644
--- a/schala-lang/language/src/reduced_ast.rs
+++ b/schala-lang/language/src/reduced_ast.rs
@@ -74,7 +74,7 @@ impl Alternative {
 #[derive(Debug, Clone)]
 pub struct Subpattern {
   pub tag: Option<usize>,
-  pub subpatterns: Vec<Subpattern>,
+  pub subpatterns: Vec<Option<Subpattern>>,
   pub bound_vars: Vec<Option<Rc<String>>>,
   pub guard: Option<Expr>,
 }
@@ -207,7 +207,7 @@ impl Pattern {
   fn to_alternative(&self, item: Vec<Stmt>, symbol_table: &SymbolTable) -> Alternative {
     use self::Pattern::*;
 
-    fn handle_symbol(symbol: &Symbol, subpatterns: &Vec<Pattern>, item: Vec<Stmt>) -> Alternative {
+    fn handle_symbol(symbol: &Symbol, subpatterns: &Vec<Pattern>) -> Subpattern {
       let tag = match symbol.spec {
         SymbolSpec::DataConstructor { index, .. } => index.clone(),
         _ => panic!("Symbol is not a data constructor - this should've been caught in type-checking"),
@@ -229,19 +229,25 @@ impl Pattern {
       let guard = None;
       let subpatterns = vec![];
 
-      Alternative {
+      Subpattern {
         tag: Some(tag),
         subpatterns,
         guard,
         bound_vars,
-        item,
       }
     }
 
     match self {
       TupleStruct(name, subpatterns) => {
         let symbol = symbol_table.lookup_by_name(name).expect(&format!("Symbol {} not found", name));
-        handle_symbol(symbol, subpatterns, item)
+        let s = handle_symbol(symbol, subpatterns);
+        Alternative {
+          tag: s.tag,
+          subpatterns: s.subpatterns,
+          guard: s.guard,
+          bound_vars: s.bound_vars,
+          item
+        }
       },
       TuplePattern(_items) => {
         unimplemented!()
@@ -290,7 +296,16 @@ impl Pattern {
           }
         },
         PatternLiteral::VarPattern(var) => match symbol_table.lookup_by_name(var) {
-          Some(symbol) => handle_symbol(symbol, &vec![], item),
+          Some(symbol) => {
+            let s = handle_symbol(symbol, &vec![]);
+            Alternative {
+              tag: s.tag,
+              subpatterns: s.subpatterns,
+              guard: s.guard,
+              bound_vars: s.bound_vars,
+              item
+            }
+          },
           None => Alternative {
             tag: None,
             subpatterns: vec![],