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Better comments for vendor/constants.js.

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Ben Newman
2013-11-13 15:28:20 -05:00
parent 2b763fc452
commit da717977ed
1 changed files with 18 additions and 2 deletions
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20
vendor/constants.js vendored
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@@ -30,12 +30,17 @@ function transform(ast, constants) {
return types.traverse(ast, function(node, traverse) {
if (namedTypes.Identifier.check(node)) {
// If the identifier is the property of a member expression
// (e.g. object.property), then it definitely is not a constant
// expression that we want to replace.
if (namedTypes.MemberExpression.check(this.parent.node) &&
this.name === 'property' &&
!this.parent.node.computed) {
return false;
}
// There could in principle be a constant called "hasOwnProperty",
// so be careful always to use Object.prototype.hasOwnProperty.
if (hasOwn.call(constants, node.name)) {
this.replace(builders.literal(constants[node.name]));
return false;
@@ -45,6 +50,8 @@ function transform(ast, constants) {
if (!constants.__DEV__) {
if (namedTypes.Identifier.check(node.callee) &&
node.callee.name === 'invariant') {
// Truncate the arguments of invariant(condition, ...)
// statements to just the condition.
node.arguments.length = 1;
}
}
@@ -52,12 +59,21 @@ function transform(ast, constants) {
} else if (namedTypes.IfStatement.check(node) &&
namedTypes.Literal.check(node.test)) {
if (node.test.value) {
node.alternate = null;
// If the alternate (then) branch is dead code, remove it.
this.get("alternate").replace();
// This is what happens when you replace a node with nothing and
// it can't be removed from a list of statements.
assert.strictEqual(node.alternate, null);
} else if (node.alternate) {
// Replace the whole if-statement with just the alternate clause.
this.replace(node.alternate);
return false;
} else {
this.replace(); // Remove the if-statement.
// Remove the entire if-statement.
this.replace();
return false;
}
}