From 4f7478d7b2f77a2e1f48514e779daf410cad5046 Mon Sep 17 00:00:00 2001
From: Luna <git@l4.pm>
Date: Mon, 1 Jul 2019 15:39:48 -0300
Subject: [PATCH] basic fndecl ast node working

---
 src/parser.zig | 76 +++++++++++++++++++++++---------------------------
 1 file changed, 35 insertions(+), 41 deletions(-)

diff --git a/src/parser.zig b/src/parser.zig
index 6142051..76b8c59 100644
--- a/src/parser.zig
+++ b/src/parser.zig
@@ -17,7 +17,6 @@ pub const Parser = struct {
     scanner: *Scanner,
 
     tokens: []Token = undefined,
-    current: usize = 0,
 
     pub fn init(allocator: *Allocator, scanner: *Scanner) Parser {
         return Parser{ .allocator = allocator, .scanner = scanner };
@@ -32,11 +31,11 @@ pub const Parser = struct {
     }
 
     fn peek(self: *Parser) Token {
-        return self.tokens[self.current];
+        return self.tokens[self.tokens.len - 1];
     }
 
     fn previous(self: *Parser) Token {
-        return self.tokens[self.current - 1];
+        return self.tokens[self.tokens.len - 2];
     }
 
     fn tokenError(self: *Parser, token: Token, msg: []const u8) Result!void {
@@ -53,45 +52,47 @@ pub const Parser = struct {
         return self.peek().ttype == .EOF;
     }
 
-    fn advance(self: *Parser) Token {
-        if (!self.isAtEnd()) self.current += 1;
-        return self.previous();
-    }
-
     fn check(self: *Parser, ttype: TokenType) bool {
         if (self.isAtEnd()) return false;
         return self.peek().ttype == ttype;
     }
 
-    fn match(self: *Parser, ttypes: []TokenType) bool {
-        for (ttypes) |ttype| {
-            if (self.check(ttype)) {
-                _ = self.advance();
-                return true;
+    fn nextToken(self: *Parser) !Token {
+        var token: Token = undefined;
+
+        while (true) {
+            var next_token_opt = try self.scanner.nextToken();
+            if (next_token_opt) |token_nice| {
+                token = token_nice;
+                break;
             }
         }
 
-        return false;
+        self.tokens = try self.allocator.realloc(
+            self.tokens,
+            self.tokens.len + 1,
+        );
+
+        self.tokens[self.tokens.len - 1] = token;
+        return token;
     }
 
-    fn matchSingle(self: *Parser, ttype: TokenType) bool {
-        if (self.check(ttype)) {
-            _ = self.advance();
-            return true;
-        }
-
-        return false;
-    }
-
-    fn consume(self: *Parser, ttype: TokenType, comptime msg: []const u8) Result!Token {
-        if (self.check(ttype)) return self.advance();
+    fn consume(self: *Parser, ttype: TokenType, comptime msg: []const u8) !Token {
+        if (self.check(ttype)) return try self.nextToken();
 
         try self.tokenError(self.peek(), msg);
         return Result.CompileError;
     }
 
     fn consumeSingle(self: *Parser, ttype: TokenType) !Token {
-        if (self.check(ttype)) return self.advance();
+        std.debug.warn("consume {}, has {}\n", ttype, self.peek().ttype);
+
+        if (self.check(ttype)) {
+            var cur = self.peek();
+            _ = try self.nextToken();
+            std.debug.warn("now has {}\n", self.peek());
+            return cur;
+        }
 
         var buf_main: [1000]u8 = undefined;
         var buf = try std.fmt.bufPrint(
@@ -112,9 +113,10 @@ pub const Parser = struct {
     }
 
     fn functionDecl(self: *Parser) !*ast.Node {
-        // get the name
-        var name = try self.consume(.Identifier, "expected function name");
+        _ = try self.consumeSingle(.Fn);
+        var name = try self.consumeSingle(.Identifier);
         _ = try self.consumeSingle(.LeftParen);
+
         return try self.mkFnDecl(name);
     }
 
@@ -132,24 +134,16 @@ pub const Parser = struct {
 
     pub fn parse(self: *Parser) !*ast.Node {
         self.tokens = try self.allocator.alloc(Token, 0);
-        var i: usize = 0;
         var root = try ast.mkRoot(self.allocator);
 
         while (true) {
-            var tok_opt = try self.scanner.nextToken();
+            var token = try self.nextToken();
 
-            if (tok_opt) |token| {
-                self.tokens = try self.allocator.realloc(self.tokens, i + 1);
-                self.tokens[i] = token;
-                i += 1;
+            if (token.ttype == .EOF) break;
 
-                if (token.ttype == .EOF) break;
-
-                var node = try self.processToken(token);
-                try root.Root.append(node);
-            } else {
-                continue;
-            }
+            var node = try self.processToken(token);
+            std.debug.warn("{}\n", node.*);
+            try root.Root.append(node);
         }
 
         return root;