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Use a directEnumArray lookup table instead of a switch

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Shachaf Ben-Kiki 2021-04-24 22:35:37 -07:00
parent 01aa74a93f
commit 33da465079
1 changed files with 30 additions and 34 deletions
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64
lib/std/zig/parse.zig
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@ -1336,45 +1336,41 @@ const Parser = struct {
// A table of binary operator information. Higher precedence numbers are
// stickier. All operators at the same precedence level should have the same
// associativity.
fn operInfo(tag: Token.Tag) OperInfo {
return switch (tag) {
.keyword_or => .{ .prec = 10, .tag = .bool_or },
const operTable = std.enums.directEnumArrayDefault(Token.Tag, OperInfo, .{ .prec = -1, .tag = Node.Tag.root }, 0, .{
.keyword_or = .{ .prec = 10, .tag = .bool_or },
.keyword_and => .{ .prec = 20, .tag = .bool_and },
.invalid_ampersands => .{ .prec = 20, .tag = .bool_and },
.keyword_and = .{ .prec = 20, .tag = .bool_and },
.invalid_ampersands = .{ .prec = 20, .tag = .bool_and },
.equal_equal => .{ .prec = 30, .tag = .equal_equal, .assoc = Assoc.none },
.bang_equal => .{ .prec = 30, .tag = .bang_equal, .assoc = Assoc.none },
.angle_bracket_left => .{ .prec = 30, .tag = .less_than, .assoc = Assoc.none },
.angle_bracket_right => .{ .prec = 30, .tag = .greater_than, .assoc = Assoc.none },
.angle_bracket_left_equal => .{ .prec = 30, .tag = .less_or_equal, .assoc = Assoc.none },
.angle_bracket_right_equal => .{ .prec = 30, .tag = .greater_or_equal, .assoc = Assoc.none },
.equal_equal = .{ .prec = 30, .tag = .equal_equal, .assoc = Assoc.none },
.bang_equal = .{ .prec = 30, .tag = .bang_equal, .assoc = Assoc.none },
.angle_bracket_left = .{ .prec = 30, .tag = .less_than, .assoc = Assoc.none },
.angle_bracket_right = .{ .prec = 30, .tag = .greater_than, .assoc = Assoc.none },
.angle_bracket_left_equal = .{ .prec = 30, .tag = .less_or_equal, .assoc = Assoc.none },
.angle_bracket_right_equal = .{ .prec = 30, .tag = .greater_or_equal, .assoc = Assoc.none },
.ampersand => .{ .prec = 40, .tag = .bit_and },
.caret => .{ .prec = 40, .tag = .bit_xor },
.pipe => .{ .prec = 40, .tag = .bit_or },
.keyword_orelse => .{ .prec = 40, .tag = .@"orelse" },
.keyword_catch => .{ .prec = 40, .tag = .@"catch" },
.ampersand = .{ .prec = 40, .tag = .bit_and },
.caret = .{ .prec = 40, .tag = .bit_xor },
.pipe = .{ .prec = 40, .tag = .bit_or },
.keyword_orelse = .{ .prec = 40, .tag = .@"orelse" },
.keyword_catch = .{ .prec = 40, .tag = .@"catch" },
.angle_bracket_angle_bracket_left => .{ .prec = 50, .tag = .bit_shift_left },
.angle_bracket_angle_bracket_right => .{ .prec = 50, .tag = .bit_shift_right },
.angle_bracket_angle_bracket_left = .{ .prec = 50, .tag = .bit_shift_left },
.angle_bracket_angle_bracket_right = .{ .prec = 50, .tag = .bit_shift_right },
.plus => .{ .prec = 60, .tag = .add },
.minus => .{ .prec = 60, .tag = .sub },
.plus_plus => .{ .prec = 60, .tag = .array_cat },
.plus_percent => .{ .prec = 60, .tag = .add_wrap },
.minus_percent => .{ .prec = 60, .tag = .sub_wrap },
.plus = .{ .prec = 60, .tag = .add },
.minus = .{ .prec = 60, .tag = .sub },
.plus_plus = .{ .prec = 60, .tag = .array_cat },
.plus_percent = .{ .prec = 60, .tag = .add_wrap },
.minus_percent = .{ .prec = 60, .tag = .sub_wrap },
.pipe_pipe => .{ .prec = 70, .tag = .merge_error_sets },
.asterisk => .{ .prec = 70, .tag = .mul },
.slash => .{ .prec = 70, .tag = .div },
.percent => .{ .prec = 70, .tag = .mod },
.asterisk_asterisk => .{ .prec = 70, .tag = .array_mult },
.asterisk_percent => .{ .prec = 70, .tag = .mul_wrap },
else => .{ .prec = -1, .tag = ast.Node.Tag.root }, // irrelevant
};
}
.pipe_pipe = .{ .prec = 70, .tag = .merge_error_sets },
.asterisk = .{ .prec = 70, .tag = .mul },
.slash = .{ .prec = 70, .tag = .div },
.percent = .{ .prec = 70, .tag = .mod },
.asterisk_asterisk = .{ .prec = 70, .tag = .array_mult },
.asterisk_percent = .{ .prec = 70, .tag = .mul_wrap },
});
fn parseExprPrecedence(p: *Parser, min_prec: i32) Error!Node.Index {
var node = try p.parsePrefixExpr();
@ -1386,7 +1382,7 @@ const Parser = struct {
while (true) {
const tok_tag = p.token_tags[p.tok_i];
const info = operInfo(tok_tag);
const info = operTable[@intCast(usize, @enumToInt(tok_tag))];
if (info.prec < min_prec or info.prec == banned_prec) {
break;
}