91 lines
2.7 KiB
JavaScript
91 lines
2.7 KiB
JavaScript
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import { countColumn } from "./misc.js"
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// STRING STREAM
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// Fed to the mode parsers, provides helper functions to make
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// parsers more succinct.
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class StringStream {
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constructor(string, tabSize, lineOracle) {
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this.pos = this.start = 0
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this.string = string
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this.tabSize = tabSize || 8
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this.lastColumnPos = this.lastColumnValue = 0
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this.lineStart = 0
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this.lineOracle = lineOracle
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}
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eol() {return this.pos >= this.string.length}
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sol() {return this.pos == this.lineStart}
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peek() {return this.string.charAt(this.pos) || undefined}
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next() {
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if (this.pos < this.string.length)
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return this.string.charAt(this.pos++)
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}
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eat(match) {
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let ch = this.string.charAt(this.pos)
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let ok
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if (typeof match == "string") ok = ch == match
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else ok = ch && (match.test ? match.test(ch) : match(ch))
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if (ok) {++this.pos; return ch}
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}
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eatWhile(match) {
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let start = this.pos
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while (this.eat(match)){}
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return this.pos > start
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}
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eatSpace() {
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let start = this.pos
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while (/[\s\u00a0]/.test(this.string.charAt(this.pos))) ++this.pos
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return this.pos > start
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}
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skipToEnd() {this.pos = this.string.length}
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skipTo(ch) {
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let found = this.string.indexOf(ch, this.pos)
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if (found > -1) {this.pos = found; return true}
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}
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backUp(n) {this.pos -= n}
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column() {
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if (this.lastColumnPos < this.start) {
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this.lastColumnValue = countColumn(this.string, this.start, this.tabSize, this.lastColumnPos, this.lastColumnValue)
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this.lastColumnPos = this.start
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}
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return this.lastColumnValue - (this.lineStart ? countColumn(this.string, this.lineStart, this.tabSize) : 0)
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}
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indentation() {
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return countColumn(this.string, null, this.tabSize) -
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(this.lineStart ? countColumn(this.string, this.lineStart, this.tabSize) : 0)
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}
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match(pattern, consume, caseInsensitive) {
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if (typeof pattern == "string") {
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let cased = str => caseInsensitive ? str.toLowerCase() : str
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let substr = this.string.substr(this.pos, pattern.length)
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if (cased(substr) == cased(pattern)) {
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if (consume !== false) this.pos += pattern.length
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return true
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}
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} else {
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let match = this.string.slice(this.pos).match(pattern)
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if (match && match.index > 0) return null
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if (match && consume !== false) this.pos += match[0].length
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return match
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}
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}
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current(){return this.string.slice(this.start, this.pos)}
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hideFirstChars(n, inner) {
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this.lineStart += n
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try { return inner() }
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finally { this.lineStart -= n }
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}
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lookAhead(n) {
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let oracle = this.lineOracle
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return oracle && oracle.lookAhead(n)
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}
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baseToken() {
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let oracle = this.lineOracle
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return oracle && oracle.baseToken(this.pos)
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}
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}
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export default StringStream
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