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add basic parser

This commit is contained in:
Luna 2019-06-05 22:06:12 -03:00
parent 3becccfba8
commit f70f2ea1ae
7 changed files with 263 additions and 41 deletions
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10
src/ast.zig
View File

@ -6,6 +6,9 @@ pub const ExprType = enum {
Binary,
Grouping,
Number,
Bool,
Nil,
String,
};
pub const Expr = union(ExprType) {
@ -13,6 +16,9 @@ pub const Expr = union(ExprType) {
Binary: BinaryExpr,
Grouping: Grouping,
Number: Number,
Bool: Bool,
Nil: Nil,
String: String,
};
pub const UnaryExpr = struct {
@ -91,3 +97,7 @@ pub fn mkNum(comptime T: type, num: T) Expr {
return expr;
}
pub const Bool = bool;
pub const Nil = void;
pub const String = []u8;

14
src/errors.zig Normal file
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@ -0,0 +1,14 @@
const std = @import("std");
pub fn report(line: usize, where: []const u8, message: []const u8) void {
std.debug.warn("[line {}] Error{}: {}", line, where, message);
}
pub fn reportN(line: usize, message: []const u8) void {
report(line, "", message);
}
pub fn reportFmt(line: usize, comptime fmt: []const u8, args: ...) void {
std.debug.warn("[line {}] Error", line);
std.debug.warn(fmt, args);
std.debug.warn("\n");
}

4
src/main.zig
View File

@ -6,6 +6,7 @@ const Allocator = std.mem.Allocator;
pub const Result = error{
Ok,
ScannerError,
CompileError,
};
@ -53,6 +54,9 @@ fn runPrompt(allocator: *Allocator) !void {
run(allocator, line) catch |err| {
switch (err) {
Result.Ok => {},
Result.ScannerError => blk: {
try stdout.print("scanner error.\n");
},
Result.CompileError => blk: {
try stdout.print("compile error.\n");
},

237
src/parser.zig
View File

@ -3,19 +3,22 @@ const scanners = @import("scanner.zig");
const main = @import("main.zig");
const ast = @import("ast.zig");
const tokens = @import("tokens.zig");
const err = @import("errors.zig");
const Allocator = std.mem.Allocator;
const Scanner = scanners.Scanner;
const AstNode = ast.AstNode;
const Token = tokens.Token;
const TokenType = tokens.TokenType;
const Result = main.Result;
const Expr = ast.Expr;
pub const Parser = struct {
allocator: *Allocator,
scanner: *Scanner,
current: Token = undefined,
root: AstNode = undefined,
tokens: []Token = undefined,
current: usize = 0,
pub fn init(allocator: *Allocator, scanner: *Scanner) Parser {
return Parser{ .allocator = allocator, .scanner = scanner };
@ -29,45 +32,223 @@ pub const Parser = struct {
return Result.CompileError;
}
fn advance(self: *Parser) !void {
var tok_opt = try self.scanner.nextToken();
if (tok_opt) |tok| {
self.current = tok;
}
fn peek(self: *Parser) Token {
return self.tokens[self.current];
}
fn accept(self: *Parser, ttype: TokenType) !bool {
if (self.current.ttype == ttype) {
try self.advance();
return true;
fn previous(self: *Parser) Token {
return self.tokens[self.current - 1];
}
fn tokenError(self: *Parser, token: Token, msg: []const u8) Result!void {
if (token.ttype == .EOF) {
err.report(token.line, " at end", msg);
} else {
return false;
err.reportFmt(token.line, " at '{}': {}", token.lexeme, msg);
}
return Result.CompileError;
}
fn synchronize(self: *Parser) void {
_ = self.advance();
while (!self.isAtEnd()) {
if (self.previous().ttype == .Semicolon) return;
switch (self.peek().ttype) {
.Struct, .Fn, .For, .If, .Return => return,
else => {},
}
_ = self.advance();
}
}
fn expect(self: *Parser, ttype: TokenType) !void {
if (!try self.accept(ttype)) {
try self.doError("expected {x}, got {}", ttype, self.current.ttype);
fn isAtEnd(self: *Parser) bool {
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;
}
}
return false;
}
fn statement(self: *Parser) !void {}
fn matchSingle(self: *Parser, ttype: TokenType) bool {
if (self.check(ttype)) {
_ = self.advance();
return true;
}
fn block(self: *Parser) !void {}
fn program(self: *Parser) !void {
try self.advance();
try self.block();
try self.expect(.EOF);
return false;
}
pub fn parse(self: *Parser) !AstNode {
self.root = AstNode{
.Program = try self.allocator.alloc(AstNode, 0),
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 equality(self: *Parser) !Expr {
var expr = try self.comparison();
while (self.match(&[]TokenType{ TokenType.BangEqual, TokenType.EqualEqual })) {
var operator = self.previous();
var right = try self.comparison();
expr = ast.mkBinary(&expr, operator, &right);
}
return expr;
}
fn comparison(self: *Parser) !Expr {
var expr = try self.addition();
while (self.match(&[]TokenType{
TokenType.Greater,
TokenType.GreaterEqual,
TokenType.Less,
TokenType.LessEqual,
})) {
var operator = self.previous();
var right = try self.addition();
expr = ast.mkBinary(&expr, operator, &right);
}
return expr;
}
fn addition(self: *Parser) !Expr {
var expr = try self.multiplication();
while (self.match(&[]TokenType{ TokenType.Minus, TokenType.Plus })) {
var operator = self.previous();
var right = try self.multiplication();
expr = ast.mkBinary(&expr, operator, &right);
}
return expr;
}
fn multiplication(self: *Parser) anyerror!Expr {
var expr = try self.unary();
while (self.match(&[]TokenType{ TokenType.Slash, TokenType.Star })) {
var operator = self.previous();
var right = try self.unary();
expr = ast.mkBinary(&expr, operator, &right);
}
return expr;
}
fn unary(self: *Parser) anyerror!Expr {
if (self.match(&[]TokenType{ TokenType.Bang, TokenType.Minus })) {
var operator = self.previous();
var right = try self.unary();
return ast.mkUnary(operator, &right);
}
return try self.primary();
}
fn doInt(self: *Parser) !Expr {
var token = self.previous();
// try to parse it as an i32 first, if that fails, do i64.
var num_32 = std.fmt.parseInt(i32, token.lexeme, 10) catch |pi_err| {
if (pi_err == error.Overflow) {
var num_64 = std.fmt.parseInt(i64, token.lexeme, 10) catch |pi_err2| {
if (pi_err2 == error.Overflow) {
try self.tokenError(token, "Failed to parse number: overflow");
return Result.CompileError;
} else {
return pi_err2;
}
};
return ast.mkNum(i64, num_64);
} else {
return pi_err;
}
};
try self.program();
return ast.mkNum(i32, num_32);
}
return self.root;
fn primary(self: *Parser) !Expr {
if (self.matchSingle(TokenType.False)) return ast.Expr{ .Bool = false };
if (self.matchSingle(TokenType.True)) return ast.Expr{ .Bool = true };
if (self.matchSingle(TokenType.None)) return ast.Expr{ .Nil = {} };
if (self.matchSingle(TokenType.Integer)) {
return try self.doInt();
}
if (self.matchSingle(TokenType.String)) {
var lexeme = self.previous().lexeme;
var slice = try self.allocator.alloc(u8, lexeme.len);
std.mem.copy(u8, slice, lexeme);
return ast.Expr{ .String = slice };
}
if (self.matchSingle(TokenType.LeftParen)) {
var expr = try self.expression();
_ = try self.consume(.RightParen, "Expect ')' after expression");
return ast.mkGrouping(&expr);
}
try self.tokenError(self.peek(), "Expect expression");
return Result.CompileError;
}
fn expression(self: *Parser) !Expr {
return try self.equality();
}
pub fn parse(self: *Parser) !?*Expr {
self.tokens = try self.allocator.alloc(Token, 0);
var i: usize = 0;
while (true) {
var tok_opt = try self.scanner.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;
}
}
std.debug.warn("{} tokens\n", i);
//return Expr{ .Number = ast.Number{ .Integer32 = 69 } };
//return self.root;
var expr = self.expression() catch |parse_err| {
return null;
};
return &expr;
}
};

30
src/runner.zig
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@ -28,7 +28,7 @@ pub const Runner = struct {
err,
);
return Result.CompileError;
return Result.ScannerError;
};
if (tok_opt) |tok| {
@ -43,20 +43,24 @@ pub const Runner = struct {
try self.testScanner(&scanner);
scanner = scanners.Scanner.init(self.allocator, code);
//var parser = Parser.init(self.allocator, &scanner);
//var tree = try parser.parse();
var parser = Parser.init(self.allocator, &scanner);
var expr_opt = try parser.parse();
var expr = ast.mkBinary(
&ast.mkUnary(
tokens.Token{ .ttype = .Minus, .lexeme = "-", .line = 1 },
&ast.mkNum(i32, 123),
),
tokens.Token{ .ttype = .Star, .lexeme = "*", .line = 1 },
&ast.mkGrouping(&ast.mkNum(f32, 45.67)),
);
//var expr = ast.mkBinary(
// &ast.mkUnary(
// tokens.Token{ .ttype = .Minus, .lexeme = "-", .line = 1 },
// &ast.mkNum(i32, 123),
// ),
// tokens.Token{ .ttype = .Star, .lexeme = "*", .line = 1 },
// &ast.mkGrouping(&ast.mkNum(f32, 45.67)),
//);
printer.printAst(&expr);
std.debug.warn("\n");
if (expr_opt) |expr_ptr| {
printer.printAst(expr_ptr);
std.debug.warn("\n");
} else {
return Result.CompileError;
}
return Result.Ok;
}

6
src/scanner.zig
View File

@ -46,6 +46,9 @@ const keywords = [][]const u8{
"return",
"struct",
"type",
"true",
"false",
"None",
};
const keyword_ttypes = []TokenType{
@ -70,6 +73,9 @@ const keyword_ttypes = []TokenType{
.Return,
.Struct,
.Type,
.True,
.False,
.None,
};
fn getKeyword(keyword: []const u8) ?TokenType {

3
src/tokens.zig
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@ -67,6 +67,9 @@ pub const TokenType = enum {
Return,
Struct,
Type,
True,
False,
None,
EOF,
};