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const std = @import("std");
const Loc = @import("loc.zig").Loc;
const Expr = @import("expr.zig").Expr;
const PropKey = @import("expr.zig").PropKey;
const Parser = @import("../parser.zig").Parser;
const Formatter = @import("../formatter.zig").Formatter;
const ParseError = @import("../parser.zig").ParseError;
pub const PatType = union(enum) {
ident: []const u8,
object: ObjectPat,
array: ArrayPat,
assign: AssignPat,
rest: RestPat,
};
pub const Pat = struct {
loc: Loc,
data: PatType,
pub fn parse(p: *Parser) ParseError!Pat {
const start = p.tok().loc.start;
switch (p.peek()) {
.identifier, .await, .yield => {
const t = p.advanceTok();
const name = p.tokenSlice(t);
return Pat{ .loc = .{ .start = start, .end = t.loc.end }, .data = .{ .ident = name } };
},
.lbrace => {
p.advance();
var props: [128]PatProp = undefined;
var count: usize = 0;
var rest: ?*const Pat = null;
while (p.peek() != .rbrace and p.peek() != .eof) {
if (p.peek() == .@"...") {
p.advance();
const pat = try Pat.parse(p);
rest = p.arena.patPtr(pat.data, pat.loc);
break;
}
if (p.peek() == .identifier) {
const name_tok = p.tok();
const name = p.tokenSlice(name_tok);
p.advance();
if (p.peek() == .@":") {
p.advance();
const val_pat = try Pat.parse(p);
props[count] = .{ .key_value = .{ .key = .{ .ident = name }, .value = p.arena.patPtr(val_pat.data, val_pat.loc) } };
count += 1;
} else {
props[count] = .{ .shorthand = name };
count += 1;
}
} else if (p.peek() == .lbracket) {
const key = try p.parsePropKey();
try p.expect(.@":");
const val_pat = try Pat.parse(p);
props[count] = .{ .key_value = .{ .key = key, .value = p.arena.patPtr(val_pat.data, val_pat.loc) } };
count += 1;
} else {
break;
}
if (!p.match(.comma)) break;
}
try p.expect(.rbrace);
return Pat{ .loc = .{ .start = start, .end = p.tok().loc.start }, .data = .{ .object = .{ .loc = .{ .start = start, .end = p.tok().loc.start }, .props = props[0..count], .rest = rest } } };
},
.lbracket => {
p.advance();
var elems: [128]?Pat = undefined;
var count: usize = 0;
var rest: ?*const Pat = null;
while (p.peek() != .rbracket and p.peek() != .eof) {
if (p.match(.comma)) {
elems[count] = null;
count += 1;
} else if (p.peek() == .@"...") {
p.advance();
const pat = try Pat.parse(p);
rest = p.arena.patPtr(pat.data, pat.loc);
break;
} else {
const pat = try Pat.parse(p);
elems[count] = pat;
count += 1;
if (!p.match(.comma)) break;
}
}
try p.expect(.rbracket);
return Pat{ .loc = .{ .start = start, .end = p.tok().loc.start }, .data = .{ .array = .{ .loc = .{ .start = start, .end = p.tok().loc.start }, .elems = elems[0..count], .rest = rest } } };
},
else => return ParseError.ExpectedParameterName,
}
}
pub fn fmt(self: @This(), f: *Formatter) void {
switch (self.data) {
.ident => |name| f.write(name),
.object => |o| o.fmt(f),
.array => |a| a.fmt(f),
.assign => |a| {
a.left.*.fmt(f);
f.write(" = ");
a.right.*.fmt(f);
},
.rest => |r| {
f.write("...");
r.arg.*.fmt(f);
},
}
}
};
pub const ObjectPat = struct {
loc: Loc,
props: []const PatProp,
rest: ?*const Pat,
pub fn fmt(self: @This(), f: *Formatter) void {
f.writeChar('{');
var first = true;
for (self.props) |prop| {
if (!first) f.write(", ");
first = false;
switch (prop) {
.key_value => |kv| {
kv.key.fmt(f);
f.write(": ");
kv.value.*.fmt(f);
},
.shorthand => |name| f.write(name),
.rest => |r| {
f.write("...");
r.*.fmt(f);
},
}
}
if (self.rest) |rest| {
if (!first) f.write(", ");
f.write("...");
rest.*.fmt(f);
}
f.writeChar('}');
}
};
pub const PatProp = union(enum) {
key_value: struct {
key: PropKey,
value: *const Pat,
},
shorthand: []const u8,
rest: *const Pat,
};
pub const ArrayPat = struct {
loc: Loc,
elems: []const ?Pat,
rest: ?*const Pat,
pub fn fmt(self: @This(), f: *Formatter) void {
f.writeChar('[');
for (self.elems, 0..) |elem, i| {
if (i > 0) f.write(", ");
if (elem) |pat| pat.fmt(f);
}
if (self.rest) |rest| {
if (self.elems.len > 0) f.write(", ");
f.write("...");
rest.*.fmt(f);
}
f.writeChar(']');
}
};
pub const AssignPat = struct {
loc: Loc,
left: *const Pat,
right: *const Expr,
};
pub const RestPat = struct {
loc: Loc,
arg: *const Pat,
};
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