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support destructured literals (#4278)

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This commit is contained in:
Alex Lam S.L
2020-11-17 00:01:24 +00:00
committed by GitHub
parent 42e34c870a
commit e5f80afc53
10 changed files with 2477 additions and 305 deletions
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103
lib/parse.js
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@@ -973,14 +973,16 @@ function parse($TEXT, options) {
if (!is("punc", ";")) {
init = is("keyword", "const")
? (next(), const_(true))
: is("keyword", "let")
? (next(), let_(true))
: is("keyword", "var")
? (next(), var_(true))
: expression(true, true);
if (is("operator", "in")) {
if (init instanceof AST_Var) {
if (init instanceof AST_Definitions) {
if (init.definitions.length > 1)
croak("Only one variable declaration allowed in for..in loop", init.start.line, init.start.col, init.start.pos);
} else if (!is_assignable(init)) {
} else if (!(is_assignable(init) || (init = to_destructured(init)) instanceof AST_Destructured)) {
croak("Invalid left-hand side in for..in loop", init.start.line, init.start.col, init.start.pos);
}
next();
@@ -1025,7 +1027,7 @@ function parse($TEXT, options) {
var argnames = [];
for (var first = true; !is("punc", ")");) {
if (first) first = false; else expect(",");
argnames.push(as_symbol(AST_SymbolFunarg));
argnames.push(maybe_destructured(AST_SymbolFunarg));
}
next();
var loop = S.in_loop;
@@ -1146,16 +1148,16 @@ function parse($TEXT, options) {
});
}
function vardefs(type, no_in, must_init) {
function vardefs(type, no_in) {
var a = [];
for (;;) {
var start = S.token;
var name = as_symbol(type);
var name = maybe_destructured(type);
var value = null;
if (is("operator", "=")) {
next();
value = expression(false, no_in);
} else if (must_init) {
} else if (!no_in && (type === AST_SymbolConst || name instanceof AST_Destructured)) {
croak("Missing initializer in declaration");
}
a.push(new AST_VarDef({
@@ -1174,7 +1176,7 @@ function parse($TEXT, options) {
var const_ = function(no_in) {
return new AST_Const({
start : prev(),
definitions : vardefs(AST_SymbolConst, no_in, true),
definitions : vardefs(AST_SymbolConst, no_in),
end : prev()
});
};
@@ -1306,7 +1308,8 @@ function parse($TEXT, options) {
unexpected();
};
function expr_list(closing, allow_trailing_comma, allow_empty) {
function expr_list(closing, allow_trailing_comma, allow_empty, parser) {
if (!parser) parser = expression;
var first = true, a = [];
while (!is("punc", closing)) {
if (first) first = false; else expect(",");
@@ -1314,7 +1317,7 @@ function parse($TEXT, options) {
if (is("punc", ",") && allow_empty) {
a.push(new AST_Hole({ start: S.token, end: S.token }));
} else {
a.push(expression(false));
a.push(parser());
}
}
next();
@@ -1449,6 +1452,54 @@ function parse($TEXT, options) {
return sym;
}
function maybe_destructured(type) {
var start = S.token;
if (is("punc", "[")) {
next();
return new AST_DestructuredArray({
start: start,
elements: expr_list("]", !options.strict, true, function() {
return maybe_destructured(type);
}),
end: prev(),
});
}
if (is("punc", "{")) {
next();
var first = true, a = [];
while (!is("punc", "}")) {
if (first) first = false; else expect(",");
// allow trailing comma
if (!options.strict && is("punc", "}")) break;
var key_start = S.token;
var key = as_property_key();
if (!is("punc", ":") && key_start.type == "name") {
a.push(new AST_DestructuredKeyVal({
start: key_start,
key: key,
value: _make_symbol(type, key_start),
end: prev(),
}));
continue;
}
expect(":");
a.push(new AST_DestructuredKeyVal({
start: key_start,
key: key,
value: maybe_destructured(type),
end: prev(),
}));
}
next();
return new AST_DestructuredObject({
start: start,
properties: a,
end: prev(),
});
}
return as_symbol(type);
}
function mark_pure(call) {
var start = call.start;
var comments = start.comments_before;
@@ -1578,11 +1629,43 @@ function parse($TEXT, options) {
return expr instanceof AST_PropAccess || expr instanceof AST_SymbolRef;
}
function to_destructured(node) {
if (node instanceof AST_Array) {
var elements = node.elements.map(to_destructured);
return all(elements, function(node) {
return node instanceof AST_Destructured || node instanceof AST_Hole || is_assignable(node);
}) ? new AST_DestructuredArray({
start: node.start,
elements: elements,
end: node.end,
}) : node;
}
if (!(node instanceof AST_Object)) return node;
var props = [];
for (var i = 0; i < node.properties.length; i++) {
var prop = node.properties[i];
if (!(prop instanceof AST_ObjectKeyVal)) return node;
var value = to_destructured(prop.value);
if (!(value instanceof AST_Destructured || is_assignable(value))) return node;
props.push(new AST_DestructuredKeyVal({
start: prop.start,
key: prop.key,
value: value,
end: prop.end,
}));
}
return new AST_DestructuredObject({
start: node.start,
properties: props,
end: node.end,
});
}
var maybe_assign = function(no_in) {
var start = S.token;
var left = maybe_conditional(no_in), val = S.token.value;
if (is("operator") && ASSIGNMENT[val]) {
if (is_assignable(left)) {
if (is_assignable(left) || val == "=" && (left = to_destructured(left)) instanceof AST_Destructured) {
next();
return new AST_Assign({
start : start,