From dc50dd1545e5554acf2a10bd92879310b173dfd6 Mon Sep 17 00:00:00 2001
From: Alex Bethel <abethel@cs.nmt.edu>
Date: Sat, 6 Aug 2022 20:04:11 -0500
Subject: [PATCH] Basic pattern parsing

---
 axc/src/parser.rs | 35 +++++++++++++++++++++++++----------
 axc/src/syntax.rs | 11 +++++------
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/axc/src/parser.rs b/axc/src/parser.rs
index 8fc0b23..fffc1c2 100644
--- a/axc/src/parser.rs
+++ b/axc/src/parser.rs
@@ -214,13 +214,9 @@ impl Default for ParserMeta {
 
 /// Parser for AlexScript code.
 pub fn parser<'a>(m: &'a ParserMeta) -> impl Parser<char, SyntaxTree, Error = Simple<char>> + 'a {
-    // parse_statement(m)
-    //     .repeated()
-    //     .map(SyntaxTree)
-    //     .then_ignore(end())
-    parse_expression(m)
-        .then_ignore(just(";").then(whitespace()))
+    parse_statement(m)
         .repeated()
+        .map(SyntaxTree)
         .then_ignore(end())
         .map(|exprs| {
             println!("{:#?}", exprs);
@@ -288,7 +284,8 @@ fn parse_func_decl<'a>(
     m: &'a ParserMeta,
 ) -> impl Parser<char, ClassMember, Error = Simple<char>> + 'a {
     keyword("def")
-        .ignore_then(ident())
+        .then_ignore(whitespace())
+        .ignore_then(ident().then_ignore(whitespace()))
         .then(parse_pattern(m).repeated())
         .then(
             just('=')
@@ -479,13 +476,31 @@ fn parse_literal(_m: &ParserMeta) -> impl Parser<char, Expr, Error = Simple<char
         .map(|(l, r)| (l + "." + &r).parse().unwrap())
         .map(Literal::Float);
 
-    choice((int, float, string)).map(Expr::Literal)
+    choice((int, float, string))
+        .then_ignore(whitespace())
+        .map(Expr::Literal)
 }
 
 fn parse_type(_m: &ParserMeta) -> impl Parser<char, Type, Error = Simple<char>> {
     todo()
 }
 
-fn parse_pattern(_m: &ParserMeta) -> impl Parser<char, Pattern, Error = Simple<char>> {
-    todo()
+fn parse_pattern(m: &ParserMeta) -> impl Parser<char, Pattern, Error = Simple<char>> {
+    choice((parse_capture_pattern(m),))
+}
+
+fn parse_capture_pattern(_m: &ParserMeta) -> impl Parser<char, Pattern, Error = Simple<char>> {
+    ident()
+        .try_map(|iden: String, span| {
+            if iden.starts_with(|c: char| c.is_lowercase()) {
+                Ok(iden)
+            } else {
+                Err(Simple::custom(
+                    span,
+                    "capture must start with lowercase letter",
+                ))
+            }
+        })
+        .then_ignore(whitespace())
+        .map(Pattern::Exact)
 }
diff --git a/axc/src/syntax.rs b/axc/src/syntax.rs
index 0c555d3..2ab0cf5 100644
--- a/axc/src/syntax.rs
+++ b/axc/src/syntax.rs
@@ -194,9 +194,8 @@ pub enum Type {
         /// The function being applied. This must be a generic type.
         function: Box<Type>,
 
-        /// The expression given as an argument to the type. This can be any expression, to allow
-        /// const generics; in most cases, though, it should be just a normal type.
-        expression: Box<Expr>,
+        /// The type given as an argument to the type.
+        expression: Box<Type>,
     },
 
     /// `(a, b)`
@@ -210,6 +209,9 @@ pub enum Type {
 /// statements.
 #[derive(Clone, Debug)]
 pub enum Pattern {
+    /// `a`
+    Capture(String),
+
     /// `(a, b)`
     Tuple(Vec<Pattern>),
 
@@ -228,9 +230,6 @@ pub enum Pattern {
     /// `Foo { a: x, b: y, ... }`
     Destructure(String, Record),
 
-    /// `a`
-    Capture(String),
-
     /// `_`
     Ignore,