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|
const std = @import("std");
const TokenizeError = error{
UnknownToken,
UnexpectedEOF,
};
pub const TokenType = enum {
ident,
intLit,
constant,
variable,
exit,
plus,
minus,
star,
slash,
semiCol,
equal,
};
pub const Token = union(TokenType) {
ident: []const u8,
intLit: i32,
constant,
variable,
exit,
plus,
minus,
star,
slash,
semiCol,
equal,
pub fn fromChar(char: u8) !Token {
return switch (char) {
'+' => .plus,
'-' => .minus,
'*' => .star,
'/' => .slash,
';' => .semiCol,
'=' => .equal,
else => TokenizeError.UnknownToken,
};
}
pub fn fromStr(str: []const u8) Token {
const eql = std.mem.eql;
if (eql(u8, str, "exit")) return .exit;
if (eql(u8, str, "const")) return .constant;
if (eql(u8, str, "var")) return .variable;
return Token{ .ident = str };
}
};
pub fn checkType(tok: Token, comptime typ: TokenType) bool {
return switch (tok) {
typ => true,
else => false,
};
}
/// Creates a tokenizer over a slice of typ
pub fn Iterator(comptime typ: type) type {
return struct {
items: []const typ,
index: usize = 0,
/// Initialize tokenizer with a slice
pub fn init(items: []const typ) Iterator(typ) {
return Iterator(typ){ .items = items };
}
/// Get current item
pub fn peekAhead(self: Iterator(typ), ahead: u32) ?typ {
if (self.index + ahead >= self.items.len) return null;
return self.items[self.index + ahead];
}
pub fn peek(self: Iterator(typ)) ?typ {
return peekAhead(self, 0);
}
/// Get current item and iterate index
pub fn next(self: *Iterator(typ)) ?typ {
const ret = self.peek();
self.index += 1;
return ret;
}
pub fn consume(self: *Iterator(typ), comptime expected: TokenType) !?typ {
if (typ != Token) return error.TokenIteratorOnly;
if (!checkType(self.peek().?, expected))
return error.ExpectedToken;
return self.next();
}
/// Skip over current item
pub fn skip(self: *Iterator(typ)) void {
self.index += 1;
}
};
}
/// Tokenizes a string of source code
pub const Tokenizer = struct {
src: Iterator(u8),
allocator: std.mem.Allocator,
toks: std.ArrayList(Token),
/// Initializes a string of source code
/// Deinitialize with Tokenizer.deinit()
pub fn init(allocator: std.mem.Allocator, src: []const u8) Tokenizer {
return Tokenizer{
.src = Iterator(u8).init(src),
.allocator = allocator,
.toks = std.ArrayList(Token).init(allocator),
};
}
/// Releases allocated memory
pub fn deinit(self: *Tokenizer) void {
for (self.toks.items) |token| {
if (checkType(token, TokenType.ident))
self.allocator.free(token.ident);
}
self.toks.deinit();
}
/// Returns an ArrayList of tokens
pub fn tokenize(self: *Tokenizer) ![]Token {
var buff = std.ArrayList(u8).init(self.allocator);
defer buff.deinit();
while (self.src.peek()) |char| {
try switch (char) {
' ', '\n', '\t' => self.src.skip(),
'0'...'9' => {
while (std.ascii.isDigit(self.src.peek().?))
try buff.append(self.src.next().?);
const num: i32 = try std.fmt.parseInt(i32, buff.items, 10);
try self.toks.append(.{ .intLit = num });
buff.clearAndFree();
},
'a'...'z', 'A'...'Z' => {
while (std.ascii.isAlphanumeric(self.src.peek().?))
try buff.append(self.src.next().?);
const str = try buff.toOwnedSlice();
const token = Token.fromStr(str);
try self.toks.append(token);
if (!checkType(token, TokenType.ident)) self.allocator.free(str);
buff.clearAndFree();
},
else => self.toks.append(try Token.fromChar(self.src.next().?)),
};
}
return self.toks.items;
}
};
test "Tokenize" {
const expect = std.testing.expect;
const testSource: []const u8 = "exit 120 + 150 - 260 * 12 / 5;";
var tokenizer = Tokenizer.init(std.testing.allocator, testSource);
defer tokenizer.deinit();
const tokens = try tokenizer.tokenize();
const expected = &[_]Token{
.exit,
.{ .intLit = 120 },
.plus,
.{ .intLit = 150 },
.minus,
.{ .intLit = 260 },
.star,
.{ .intLit = 12 },
.slash,
.{ .intLit = 5 },
.semiCol,
};
for (tokens, expected) |act, exp| {
switch (act) {
.exit => |v| try expect(v == exp.exit),
.intLit => |v| try expect(v == exp.intLit),
.semiCol => |v| try expect(v == exp.semiCol),
.plus => |v| try expect(v == exp.plus),
.minus => |v| try expect(v == exp.minus),
.star => |v| try expect(v == exp.star),
.slash => |v| try expect(v == exp.slash),
else => try expect(1 == 0),
}
}
}
|
