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index.js
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index.js
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import detectIndent from "detect-indent";
import SourceMap from "./source-map";
import * as messages from "babel-messages";
import Printer from "./printer";
import type {Format} from "./printer";
/**
* Babel's code generator, turns an ast into code, maintaining sourcemaps,
* user preferences, and valid output.
*/
class Generator extends Printer {
constructor(ast, opts, code) {
opts = opts || {};
const tokens = ast.tokens || [];
let format = normalizeOptions(code, opts, tokens);
let map = opts.sourceMaps ? new SourceMap(opts, code) : null;
super(format, map, tokens);
this.ast = ast;
}
ast: Object;
/**
* Generate code and sourcemap from ast.
*
* Appends comments that weren't attached to any node to the end of the generated output.
*/
generate() {
return super.generate(this.ast);
}
}
/**
* Normalize generator options, setting defaults.
*
* - Detects code indentation.
* - If `opts.compact = "auto"` and the code is over 100KB, `compact` will be set to `true`.
*/
function normalizeOptions(code, opts, tokens): Format {
let style = " ";
if (code && typeof code === "string") {
let indent = detectIndent(code).indent;
if (indent && indent !== " ") style = indent;
}
let format = {
auxiliaryCommentBefore: opts.auxiliaryCommentBefore,
auxiliaryCommentAfter: opts.auxiliaryCommentAfter,
shouldPrintComment: opts.shouldPrintComment,
retainLines: opts.retainLines,
comments: opts.comments == null || opts.comments,
compact: opts.compact,
minified: opts.minified,
concise: opts.concise,
quotes: opts.quotes || findCommonStringDelimiter(code, tokens),
indent: {
adjustMultilineComment: true,
style: style,
base: 0
}
};
if (format.minified) {
format.compact = true;
format.shouldPrintComment = format.shouldPrintComment || (() => format.comments);
} else {
format.shouldPrintComment = format.shouldPrintComment || ((value) => format.comments ||
(value.indexOf("@license") >= 0 || value.indexOf("@preserve") >= 0));
}
if (format.compact === "auto") {
format.compact = code.length > 100000; // 100KB
if (format.compact) {
console.error("[BABEL] " + messages.get("codeGeneratorDeopt", opts.filename, "100KB"));
}
}
if (format.compact) {
format.indent.adjustMultilineComment = false;
}
return format;
}
/**
* Determine if input code uses more single or double quotes.
*/
function findCommonStringDelimiter(code, tokens) {
const DEFAULT_STRING_DELIMITER = "double";
if (!code) {
return DEFAULT_STRING_DELIMITER;
}
let occurences = {
single: 0,
double: 0
};
let checked = 0;
for (let i = 0; i < tokens.length; i++) {
let token = tokens[i];
if (token.type.label !== "string") continue;
let raw = code.slice(token.start, token.end);
if (raw[0] === "'") {
occurences.single++;
} else {
occurences.double++;
}
checked++;
if (checked >= 3) break;
}
if (occurences.single > occurences.double) {
return "single";
} else {
return "double";
}
}
/**
* We originally exported the Generator class above, but to make it extra clear that it is a private API,
* we have moved that to an internal class instance and simplified the interface to the two public methods
* that we wish to support.
*/
export class CodeGenerator {
constructor(ast, opts, code) {
this._generator = new Generator(ast, opts, code);
}
generate() {
return this._generator.generate();
}
}
export default function (ast: Object, opts: Object, code: string): Object {
let gen = new Generator(ast, opts, code);
return gen.generate();
}