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