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perf: improve speed of parsing #16

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Merged
merged 1 commit into from
Feb 8, 2023
Merged

perf: improve speed of parsing #16

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140 changes: 66 additions & 74 deletions index.js
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Original file line number Diff line number Diff line change
@@ -1,97 +1,89 @@
'use strict'

exports.parse = function (source, transform) {
return new ArrayParser(source, transform).parse()
return parsePostgresArray(source, transform)
}

class ArrayParser {
constructor (source, transform) {
this.source = source
this.transform = transform || identity
this.position = 0
this.entries = []
this.recorded = []
this.dimension = 0
}
function parsePostgresArray (source, transform, nested = false) {
let character = ''
let quote = false
let position = 0
let dimension = 0
const entries = []
let recorded = ''

isEof () {
return this.position >= this.source.length
}
const newEntry = function (includeEmpty) {
let entry = recorded

nextCharacter () {
const character = this.source[this.position++]
if (character === '\\') {
return {
value: this.source[this.position++],
escaped: true
if (entry.length > 0 || includeEmpty) {
if (entry === 'NULL' && !includeEmpty) {
entry = null
}
}
return {
value: character,
escaped: false

if (entry !== null && transform) {
entry = transform(entry)
}

entries.push(entry)
recorded = ''
}
}

record (character) {
this.recorded.push(character)
}
if (source[0] === '[') {
while (position < source.length) {
const char = source[position++]

newEntry (includeEmpty) {
let entry
if (this.recorded.length > 0 || includeEmpty) {
entry = this.recorded.join('')
if (entry === 'NULL' && !includeEmpty) {
entry = null
}
if (entry !== null) entry = this.transform(entry)
this.entries.push(entry)
this.recorded = []
if (char === '=') { break }
}
}

consumeDimensions () {
if (this.source[0] === '[') {
while (!this.isEof()) {
const char = this.nextCharacter()
if (char.value === '=') break
}
while (position < source.length) {
let escaped = false
character = source[position++]

if (character === '\\') {
character = source[position++]
escaped = true
}
}

parse (nested) {
let character, parser, quote
this.consumeDimensions()
while (!this.isEof()) {
character = this.nextCharacter()
if (character.value === '{' && !quote) {
this.dimension++
if (this.dimension > 1) {
parser = new ArrayParser(this.source.substr(this.position - 1), this.transform)
this.entries.push(parser.parse(true))
this.position += parser.position - 2
}
} else if (character.value === '}' && !quote) {
this.dimension--
if (!this.dimension) {
this.newEntry()
if (nested) return this.entries
if (character === '{' && !quote) {
dimension++

if (dimension > 1) {
const parser = parsePostgresArray(source.substr(position - 1), transform, true)

entries.push(parser.entries)
position += parser.position - 2
}
} else if (character === '}' && !quote) {
dimension--

if (!dimension) {
newEntry()

if (nested) {
return {
entries,
position
}
}
} else if (character.value === '"' && !character.escaped) {
if (quote) this.newEntry(true)
quote = !quote
} else if (character.value === ',' && !quote) {
this.newEntry()
} else {
this.record(character.value)
}
} else if (character === '"' && !escaped) {
if (quote) {
newEntry(true)
}

quote = !quote
} else if (character === ',' && !quote) {
newEntry()
} else {
recorded += character
}
if (this.dimension !== 0) {
throw new Error('array dimension not balanced')
}
return this.entries
}
}

function identity (value) {
return value
if (dimension !== 0) {
throw new Error('array dimension not balanced')
}

return entries
}