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