src/ast.zig

@@ -10,7 +10,7 @@ pub const NodeType = enum {
 };
 
 pub const FnDecl = struct {
-    func_name: Token,
+    func_name: []const u8,
 };
 
 pub const Node = union(NodeType) {

src/parser.zig

@@ -17,6 +17,7 @@ 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 };
@@ -31,11 +32,11 @@ pub const Parser = struct {
     }
 
     fn peek(self: *Parser) Token {
-        return self.tokens[self.tokens.len - 1];
+        return self.tokens[self.current];
     }
 
     fn previous(self: *Parser) Token {
-        return self.tokens[self.tokens.len - 2];
+        return self.tokens[self.current - 1];
     }
 
     fn tokenError(self: *Parser, token: Token, msg: []const u8) Result!void {
@@ -52,98 +53,85 @@ 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 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;
+    fn match(self: *Parser, ttypes: []TokenType) bool {
+        for (ttypes) |ttype| {
+            if (self.check(ttype)) {
+                _ = self.advance();
+                return true;
             }
         }
 
-        self.tokens = try self.allocator.realloc(
-            self.tokens,
-            self.tokens.len + 1,
-        );
-
-        self.tokens[self.tokens.len - 1] = token;
-        return token;
+        return false;
     }
 
-    fn consume(self: *Parser, ttype: TokenType, comptime msg: []const u8) !Token {
-        if (self.check(ttype)) return try self.nextToken();
+    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();
 
         try self.tokenError(self.peek(), msg);
         return Result.CompileError;
     }
 
-    fn consumeSingle(self: *Parser, ttype: TokenType) !Token {
-        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(
-            buf_main[0..],
-            "expected {}, got {}",
-            ttype,
-            self.peek().ttype,
-        );
-        try self.tokenError(self.peek(), buf);
-
-        return Result.CompileError;
-    }
-
-    fn mkFnDecl(self: *Parser, name: Token) !*ast.Node {
-        var node = try self.allocator.create(Node);
-        node.* = Node{ .FnDecl = ast.FnDecl{ .func_name = name } };
+    fn mkFnDecl(self: *Parser, name: []const u8) !*ast.Node {
+        var node = try self.allocator.create(Node.FnDecl);
+        node.* = Node.FnDecl{ .name = name };
         return node;
     }
 
     fn functionDecl(self: *Parser) !*ast.Node {
-        _ = try self.consumeSingle(.Fn);
-        var name = try self.consumeSingle(.Identifier);
-        _ = try self.consumeSingle(.LeftParen);
-
+        // get the name
+        var name = try self.consume(.Identifier, "expected function name");
         return try self.mkFnDecl(name);
     }
 
-    fn processToken(self: *Parser, token: Token) !*ast.Node {
-        var node = switch (token.ttype) {
-            .Fn => try self.functionDecl(),
+    fn processToken(self: *Parser, token: Token) Result!ast.Node {
+        switch (token.ttype) {
+            //.Fn => try self.functionDecl(),
             else => blk: {
                 try self.doError("TODO handle {}\n", token.ttype);
                 return Result.CompileError;
             },
-        };
-
-        return node;
+        }
     }
 
     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 token = try self.nextToken();
+            var tok_opt = try self.scanner.nextToken();
 
-            if (token.ttype == .EOF) break;
+            if (tok_opt) |token| {
+                self.tokens = try self.allocator.realloc(self.tokens, i + 1);
+                self.tokens[i] = token;
+                i += 1;
 
-            var node = try self.processToken(token);
-            std.debug.warn("{}\n", node.*);
-            try root.Root.append(node);
+                if (token.ttype == .EOF) break;
+
+                var node = try self.processToken(token);
+                try root.Root.append(&node);
+            } else {
+                continue;
+            }
         }
 
         return root;

src/scanner.zig

@@ -110,10 +110,6 @@ pub const Scanner = struct {
         return self.source[self.current - 1];
     }
 
-    fn rollback(self: *Scanner) void {
-        self.current -= 1;
-    }
-
     pub fn currentLexeme(self: *Scanner) []const u8 {
         return self.source[self.start..self.current];
     }
@@ -249,9 +245,6 @@ pub const Scanner = struct {
             _ = self.advance();
         }
 
-        // ugly hack.
-        self.rollback();
-
         // after reading the identifier, we check
         // if it is any of our keywords, if it is, then we add
         // the specificed keyword type. if not, just .IDENTIFIER