Hash :
3c61c8f7
Author :
Date :
2021-10-14T14:01:11
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'use strict';
/**
* @typedef TokenStreamItem
* @property {string} type
* @property {string | Array<string|TokenStreamItem>} content
*
* @typedef {Array<string|TokenStreamItem>} TokenStream
*
* @typedef {Array<string | [string, string | Array]>} SimplifiedTokenStream
*
* @typedef {Array<PrettyTokenStreamItem>} PrettyTokenStream
* @typedef {string | LineBreakItem | GlueItem | [string, string | Array]} PrettyTokenStreamItem
*/
module.exports = {
/**
* Simplifies the token stream to ease the matching with the expected token stream.
*
* * Strings are kept as-is
* * In arrays each value is transformed individually
* * Values that are empty (empty arrays or strings only containing whitespace)
*
* @param {TokenStream} tokenStream
* @returns {SimplifiedTokenStream}
*/
simplify: function simplify(tokenStream) {
return tokenStream
.map(innerSimple)
.filter(value => !(typeof value === 'string' && isBlank(value)));
/**
* @param {string | TokenStreamItem} value
* @returns {string | [string, string | Array]}
*/
function innerSimple(value) {
if (typeof value === 'object') {
if (Array.isArray(value.content)) {
return [value.type, simplify(value.content)];
} else {
return [value.type, value.content];
}
} else {
return value;
}
}
},
/**
* @param {TokenStream} tokenStream
* @param {string} [indentation]
* @returns {string}
*/
prettyprint(tokenStream, indentation) {
return printPrettyTokenStream(toPrettyTokenStream(tokenStream), undefined, indentation);
}
};
/**
* This item indicates that one or multiple line breaks are present between the preceding and following items in the
* source token stream.
*
* Only if an item is enabled will it appear in the pretty-printed token stream.
*/
class LineBreakItem {
/** @param {number} sourceCount */
constructor(sourceCount) {
this.sourceCount = sourceCount;
this.enabled = false;
}
}
/**
* This item indicates the the preceding and following items are to be printed on the same line in the pretty-printed
* token stream.
*/
class GlueItem { }
/**
* @param {TokenStream} tokenStream
* @param {number} [level]
* @returns {PrettyTokenStream}
*/
function toPrettyTokenStream(tokenStream, level = 0) {
/** @type {PrettyTokenStream} */
const prettyStream = [];
for (const token of tokenStream) {
if (typeof token === 'string') {
if (isBlank(token)) {
// blank string
const lineBreaks = countLineBreaks(token);
if (lineBreaks > 0) {
prettyStream.push(new LineBreakItem(lineBreaks));
}
} else {
// might start with line breaks
const startLineBreaks = countLineBreaks(/^\s*/.exec(token)[0]);
if (startLineBreaks > 0) {
prettyStream.push(new LineBreakItem(startLineBreaks));
}
prettyStream.push(token);
const endLineBreaks = countLineBreaks(/\s*$/.exec(token)[0]);
if (endLineBreaks > 0) {
prettyStream.push(new LineBreakItem(endLineBreaks));
}
}
} else {
prettyStream.push(innerSimple(token));
}
}
/**
* @param {TokenStreamItem} value
* @returns {[string, string | Array]}
*/
function innerSimple(value) {
if (Array.isArray(value.content)) {
return [value.type, toPrettyTokenStream(value.content, level + 1)];
} else {
return [value.type, value.content];
}
}
prettyFormat(prettyStream, (level + 1) * 4);
return prettyStream;
}
/**
* @param {PrettyTokenStream} prettyStream
* @param {number} indentationWidth
* @returns {void}
*/
function prettyFormat(prettyStream, indentationWidth) {
// The maximum number of (glued) tokens per line
const MAX_TOKEN_PER_LINE = 5;
// The maximum number of characters per line
// (this is based on an estimation. The actual output might be longer.)
const MAX_PRINT_WIDTH = 80 - indentationWidth;
prettyTrimLineBreaks(prettyStream);
// enable all line breaks with >=2 breaks in the source token stream
prettyEnableLineBreaks(prettyStream, br => br.sourceCount >= 2);
const ranges = prettySplit(prettyStream, br => br instanceof LineBreakItem && br.enabled);
for (const group of ranges) {
if (prettySomeLineBreak(group, true, br => br.enabled)) {
// Since we just split by enabled line break, only nested line breaks can be enabled. This usually
// indicates complex token streams, so let's just enable all line breaks and call it a day.
prettyEnableLineBreaks(group, () => true);
} else {
// try to optimize for the pattern /<token>{1,MAX_TOKEN_PER_LINE}(\n<token>{1,MAX_TOKEN_PER_LINE})*/
const lines = prettySplit(group, i => i instanceof LineBreakItem);
/**
* Returns whether lines can generally be glued together (no line breaks within lines and don't glue with
* nested tokens).
*/
function glueable() {
return lines.every(g => {
if (g.length > 1) {
if (prettyContainsNonTriviallyNested(g)) {
// the token with nested tokens might be glued together with other tokens and we can't allow
// that to happen
return false;
} else {
return true;
}
} else {
// we can safely ignore all tokens that are on their own line
return true;
}
});
}
function tokensPerLine() {
return lines.map(g => prettyCountTokens(g, true));
}
/**
* Returns an estimate for the output length each line will have
*/
function widthPerLine() {
return lines.map(g => {
if (g.length > 1) {
return g
.map(item => {
if (isToken(item)) {
if (typeof item === 'string') {
return ', '.length + JSON.stringify(item).length;
} else {
return ', '.length + JSON.stringify(item).length + ' '.length;
}
} else {
return 0;
}
})
.reduce((a, b) => a + b, 0) - ', '.length;
} else {
// we don't really care about the print width of a single-token line
return 1;
}
});
}
const glueTokens = glueable()
// at most this many tokens per line
&& Math.max(...tokensPerLine()) <= MAX_TOKEN_PER_LINE
// the output of each line can be at most this many characters long
&& Math.max(...widthPerLine()) <= MAX_PRINT_WIDTH
// We need to have at least 2 lines in this group OR this group isn't the only group in the stream.
// This will prevent all tokens of a really short token stream to be glued together.
&& (lines.length > 1 || ranges.length > 1);
if (glueTokens) {
prettyGlueTogetherAll(prettyStream, group);
} else {
const flatTokenCount = prettyCountTokens(group, false);
const deepTokenCount = prettyCountTokens(group, true);
if (
// prevent a one-token-per-line situation
flatTokenCount > lines.length &&
// require at least 2 tokens per line on average
deepTokenCount >= lines.length * 2
) {
prettyEnableLineBreaks(group, () => true);
}
}
}
}
}
/**
* @param {PrettyTokenStream} prettyStream
* @param {number} [indentationLevel]
* @param {string} [indentationChar]
* @returns {string}
*/
function printPrettyTokenStream(prettyStream, indentationLevel = 1, indentationChar = ' ') {
// can't use tabs because the console will convert one tab to four spaces
const indentation = new Array(indentationLevel + 1).join(indentationChar);
let out = '';
out += '[\n';
let glued = false;
prettyStream.forEach((item, i) => {
if (item instanceof LineBreakItem) {
if (item.enabled) {
out += '\n';
}
} else if (item instanceof GlueItem) {
out = out.trimEnd();
if (out[out.length - 1] === ',') {
out += ' ';
}
glued = true;
} else {
if (glued) {
glued = false;
} else {
out += indentation;
}
if (typeof item === 'string') {
out += JSON.stringify(item);
} else {
const name = item[0];
const content = item[1];
out += '[' + JSON.stringify(name) + ', ';
if (typeof content === 'string') {
// simple string literal
out += JSON.stringify(content);
} else if (content.length === 1 && typeof content[0] === 'string') {
// token stream that only contains a single string literal
out += JSON.stringify(content);
} else {
// token stream
out += printPrettyTokenStream(content, indentationLevel + 1, indentationChar);
}
out += ']';
}
const lineEnd = (i === prettyStream.length - 1) ? '\n' : ',\n';
out += lineEnd;
}
});
out += indentation.substr(indentationChar.length) + ']';
return out;
}
/**
* Returns whether the given string is empty or contains only whitespace characters.
*
* @param {string} str
* @returns {boolean}
*/
function isBlank(str) {
return /^\s*$/.test(str);
}
/**
* @param {string} str
* @returns {number}
*/
function countLineBreaks(str) {
return str.split(/\r\n?|\n/).length - 1;
}
/**
* Trim all line breaks at the start and at the end of the pretty stream.
*
* @param {PrettyTokenStream} prettyStream
* @returns {void}
*/
function prettyTrimLineBreaks(prettyStream) {
let value;
while ((value = prettyStream[0])) {
if (value instanceof LineBreakItem) {
prettyStream.shift();
} else {
break;
}
}
while ((value = prettyStream[prettyStream.length - 1])) {
if (value instanceof LineBreakItem) {
prettyStream.pop();
} else {
break;
}
}
}
/**
* Enables all line breaks in the pretty token stream (but not in nested token stream) that contain at least some
* number of line breaks in the source token stream.
*
* @param {PrettyTokenStream} prettyStream
* @param {(item: LineBreakItem) => boolean} cond
*/
function prettyEnableLineBreaks(prettyStream, cond) {
prettyStream.forEach(token => {
if (token instanceof LineBreakItem && cond(token)) {
token.enabled = true;
}
});
}
/**
* Splits the given pretty stream on all items for which `cond` return `true`. The items for which `cond` returns
* `true` will not be part of any of the created streams. No empty streams will be returned.
*
* @param {PrettyTokenStream} prettyStream
* @param {(item: PrettyTokenStreamItem) => boolean} cond
* @returns {PrettyTokenStream[]}
*/
function prettySplit(prettyStream, cond) {
/** @type {PrettyTokenStream[]} */
const result = [];
/** @type {PrettyTokenStream} */
let current = [];
for (const item of prettyStream) {
if (cond(item)) {
if (current.length > 0) {
result.push(current);
current = [];
}
} else {
current.push(item);
}
}
if (current.length > 0) {
result.push(current);
current = [];
}
return result;
}
/**
* @param {PrettyTokenStream} prettyStream
* @param {boolean} recursive
* @param {(item: LineBreakItem) => boolean} cond
* @returns {boolean}
*/
function prettySomeLineBreak(prettyStream, recursive, cond) {
for (const item of prettyStream) {
if (item instanceof LineBreakItem && cond(item)) {
return true;
} else if (recursive && isNested(item) && prettySomeLineBreak(item[1], true, cond)) {
return true;
}
}
return false;
}
/**
* @param {PrettyTokenStream} prettyStream
* @returns {boolean}
*/
function prettyContainsNonTriviallyNested(prettyStream) {
for (const item of prettyStream) {
if (isNested(item) && !isTriviallyNested(item)) {
return true;
}
}
return false;
}
/**
* @param {PrettyTokenStream} prettyStream
* @param {boolean} recursive
* @returns {number}
*/
function prettyCountTokens(prettyStream, recursive) {
let count = 0;
for (const item of prettyStream) {
if (isToken(item)) {
count++;
if (recursive && isNested(item) && !isTriviallyNested(item)) {
count += prettyCountTokens(item[1], true);
}
}
}
return count;
}
/**
* Adds glue between the given tokens in the given stream.
*
* @param {PrettyTokenStream} prettyStream
* @param {string | [string, string | any[]]} prev
* @param {string | [string, string | any[]]} next
*/
function prettyGlueTogether(prettyStream, prev, next) {
// strings may appear more than once in the stream, so we have to search for tokens.
if (typeof prev !== 'string') {
let index = prettyStream.indexOf(prev);
if (index === -1 || prettyStream[index + 1] !== next) {
throw new Error('Cannot glue: At least one of the tokens is not part of the given token stream.');
}
prettyStream.splice(index + 1, 0, new GlueItem());
} else {
let index = prettyStream.indexOf(next);
if (index === -1 || prettyStream[index - 1] !== prev) {
throw new Error('Cannot glue: At least one of the tokens is not part of the given token stream.');
}
prettyStream.splice(index, 0, new GlueItem());
}
}
/**
* Glues together all token in the given slice of the given token stream.
*
* @param {PrettyTokenStream} prettyStream
* @param {PrettyTokenStream} slice
*/
function prettyGlueTogetherAll(prettyStream, slice) {
for (let i = 1, l = slice.length; i < l; i++) {
const prev = slice[i - 1];
const next = slice[i];
if (isToken(prev) && isToken(next)) {
prettyGlueTogether(prettyStream, prev, next);
}
}
}
/**
* @param {PrettyTokenStreamItem} item
* @returns {item is (string | [string, string | any[]])}
*/
function isToken(item) {
return typeof item === 'string' || Array.isArray(item);
}
/**
* @param {PrettyTokenStreamItem} item
* @returns {item is [string, any[]]}
*/
function isNested(item) {
return Array.isArray(item) && Array.isArray(item[1]);
}
/**
* @param {PrettyTokenStreamItem} item
* @returns {item is [string, [string]]}
*/
function isTriviallyNested(item) {
return isNested(item) && item[1].length === 1 && typeof item[1][0] === 'string';
}