sucrase
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Super-fast alternative to Babel for when you can target modern JS runtimes
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JavaScript
/**
* Implementation of babel-plugin-transform-react-display-name, which adds a
* display name to usages of React.createClass and createReactClass.
*
* This implementation has the following limitations compared with the
* - It does not handle `export default React.createClass`, using the filename,
* since Sucrase currently does not know the name of the current file.
*/
export default class ReactDisplayNameTransformer {
constructor(rootTransformer, tokens, identifierReplacer) {
this.rootTransformer = rootTransformer;
this.tokens = tokens;
this.identifierReplacer = identifierReplacer;
}
preprocess() {
}
process() {
const startIndex = this.tokens.currentIndex();
if (this.tokens.matchesName('createReactClass')) {
const newName = this.identifierReplacer.getIdentifierReplacement('createReactClass');
if (newName) {
this.tokens.replaceToken(`(0, ${newName})`);
}
else {
this.tokens.copyToken();
}
this.tryProcessCreateClassCall(startIndex);
return true;
}
if (this.tokens.matches(['name', '.', 'name']) &&
this.tokens.matchesName('React') &&
this.tokens.matchesNameAtIndex(this.tokens.currentIndex() + 2, 'createClass')) {
const newName = this.identifierReplacer.getIdentifierReplacement('React');
if (newName) {
this.tokens.replaceToken(newName);
this.tokens.copyToken();
this.tokens.copyToken();
}
else {
this.tokens.copyToken();
this.tokens.copyToken();
this.tokens.copyToken();
}
this.tryProcessCreateClassCall(startIndex);
return true;
}
return false;
}
/**
* This is called with the token position at the open-paren.
*/
tryProcessCreateClassCall(startIndex) {
const displayName = this.findDisplayName(startIndex);
if (!displayName) {
return;
}
if (this.classNeedsDisplayName()) {
this.tokens.copyExpectedToken('(');
this.tokens.copyExpectedToken('{');
this.tokens.appendCode(`displayName: '${displayName}',`);
this.rootTransformer.processBalancedCode();
this.tokens.copyExpectedToken('}');
this.tokens.copyExpectedToken(')');
}
}
findDisplayName(startIndex) {
if (this.tokens.matchesAtIndex(startIndex - 2, ['name', '=']) &&
!this.tokens.matchesAtIndex(startIndex - 3, ['.'])) {
// This is an assignment (or declaration) with an identifier LHS, so use
// that identifier name.
return this.tokens.tokens[startIndex - 2].value;
}
if (this.tokens.matchesAtIndex(startIndex - 2, ['name', ':']) &&
this.tokens.tokens[startIndex - 2].contextName === 'object' &&
(this.tokens.tokens[startIndex - 3].type.label === ',' ||
this.tokens.tokens[startIndex - 3].type.label === '{')) {
// This is an object literal value.
return this.tokens.tokens[startIndex - 2].value;
}
return null;
}
/**
* We only want to add a display name when this is a function call containing
* one argument, which is an object literal without `displayName` as an
* existing key.
*/
classNeedsDisplayName() {
let index = this.tokens.currentIndex();
if (!this.tokens.matches(['(', '{'])) {
return false;
}
// Currently augmentTokenContext starts the block at one after the {, so we
// expect any displayName key to be in that context. We need to ignore other
// other contexts to avoid matching nested displayName keys.
const objectStartIndex = index + 2;
for (; index < this.tokens.tokens.length; index++) {
const token = this.tokens.tokens[index];
if (token.type.label === '}' &&
token.contextName === 'object' &&
token.contextStartIndex === objectStartIndex) {
index++;
break;
}
if (this.tokens.matchesNameAtIndex(index, 'displayName') &&
this.tokens.matchesAtIndex(index + 1, [':']) &&
(this.tokens.matchesAtIndex(index - 1, [',']) || this.tokens.matchesAtIndex(index - 1, ['{'])) &&
token.contextName === 'object' &&
token.contextStartIndex === objectStartIndex) {
// We found a displayName key, so bail out.
return false;
}
}
// If we got this far, we know we have createClass with an object with no
// display name, so we want to proceed as long as that was the only argument.
return this.tokens.matchesAtIndex(index, [')']) ||
this.tokens.matchesAtIndex(index, [',', ')']);
}
getPrefixCode() {
return '';
}
getSuffixCode() {
return '';
}
}