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StringStream.min.js (2799B)

      1 import { countColumn } from "./misc.js"
      2 
      3 // STRING STREAM
      4 
      5 // Fed to the mode parsers, provides helper functions to make
      6 // parsers more succinct.
      7 
      8 class StringStream {
      9   constructor(string, tabSize, lineOracle) {
     10     this.pos = this.start = 0
     11     this.string = string
     12     this.tabSize = tabSize || 8
     13     this.lastColumnPos = this.lastColumnValue = 0
     14     this.lineStart = 0
     15     this.lineOracle = lineOracle
     16   }
     17 
     18   eol() {return this.pos >= this.string.length}
     19   sol() {return this.pos == this.lineStart}
     20   peek() {return this.string.charAt(this.pos) || undefined}
     21   next() {
     22     if (this.pos < this.string.length)
     23       return this.string.charAt(this.pos++)
     24   }
     25   eat(match) {
     26     let ch = this.string.charAt(this.pos)
     27     let ok
     28     if (typeof match == "string") ok = ch == match
     29     else ok = ch && (match.test ? match.test(ch) : match(ch))
     30     if (ok) {++this.pos; return ch}
     31   }
     32   eatWhile(match) {
     33     let start = this.pos
     34     while (this.eat(match)){}
     35     return this.pos > start
     36   }
     37   eatSpace() {
     38     let start = this.pos
     39     while (/[\s\u00a0]/.test(this.string.charAt(this.pos))) ++this.pos
     40     return this.pos > start
     41   }
     42   skipToEnd() {this.pos = this.string.length}
     43   skipTo(ch) {
     44     let found = this.string.indexOf(ch, this.pos)
     45     if (found > -1) {this.pos = found; return true}
     46   }
     47   backUp(n) {this.pos -= n}
     48   column() {
     49     if (this.lastColumnPos < this.start) {
     50       this.lastColumnValue = countColumn(this.string, this.start, this.tabSize, this.lastColumnPos, this.lastColumnValue)
     51       this.lastColumnPos = this.start
     52     }
     53     return this.lastColumnValue - (this.lineStart ? countColumn(this.string, this.lineStart, this.tabSize) : 0)
     54   }
     55   indentation() {
     56     return countColumn(this.string, null, this.tabSize) -
     57       (this.lineStart ? countColumn(this.string, this.lineStart, this.tabSize) : 0)
     58   }
     59   match(pattern, consume, caseInsensitive) {
     60     if (typeof pattern == "string") {
     61       let cased = str => caseInsensitive ? str.toLowerCase() : str
     62       let substr = this.string.substr(this.pos, pattern.length)
     63       if (cased(substr) == cased(pattern)) {
     64         if (consume !== false) this.pos += pattern.length
     65         return true
     66       }
     67     } else {
     68       let match = this.string.slice(this.pos).match(pattern)
     69       if (match && match.index > 0) return null
     70       if (match && consume !== false) this.pos += match[0].length
     71       return match
     72     }
     73   }
     74   current(){return this.string.slice(this.start, this.pos)}
     75   hideFirstChars(n, inner) {
     76     this.lineStart += n
     77     try { return inner() }
     78     finally { this.lineStart -= n }
     79   }
     80   lookAhead(n) {
     81     let oracle = this.lineOracle
     82     return oracle && oracle.lookAhead(n)
     83   }
     84   baseToken() {
     85     let oracle = this.lineOracle
     86     return oracle && oracle.baseToken(this.pos)
     87   }
     88 }
     89 
     90 export default StringStream