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Allow Parser pattern size to be parametrizable #152

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118 changes: 64 additions & 54 deletions Parser.js
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Original file line number Diff line number Diff line change
@@ -1,21 +1,8 @@
'use strict';

const Utf8Stream = require('./utils/Utf8Stream');

const patterns = {
value1: /^(?:[\"\{\[\]\-\d]|true\b|false\b|null\b|\s{1,256})/,
string: /^(?:[^\"\\]{1,256}|\\[bfnrt\"\\\/]|\\u[\da-fA-F]{4}|\")/,
key1: /^(?:[\"\}]|\s{1,256})/,
colon: /^(?:\:|\s{1,256})/,
comma: /^(?:[\,\]\}]|\s{1,256})/,
ws: /^\s{1,256}/,
numberStart: /^\d/,
numberDigit: /^\d{0,256}/,
numberFraction: /^[\.eE]/,
numberExponent: /^[eE]/,
numberExpSign: /^[-+]/
};
const MAX_PATTERN_SIZE = 16;
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@mbenedettini mbenedettini Jun 25, 2024

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this const name is now confusing (compared to DEFAULT_PATTERN_SIZE) but I couldn't find a better name

const DEFAULT_PATTERN_SIZE = 256;

let noSticky = true;
try {
Expand All @@ -25,17 +12,35 @@ try {
// suppress
}

!noSticky &&
Object.keys(patterns).forEach(key => {
let src = patterns[key].source.slice(1); // lop off ^
if (src.slice(0, 3) === '(?:' && src.slice(-1) === ')') {
src = src.slice(3, -1);
}
patterns[key] = new RegExp(src, 'y');
});
const getPatterns = (patternSize) => {
const patterns = {
value1: new RegExp(`^(?:[\"\\{\\[\\]\\-\\d]|true\\b|false\\b|null\\b|\\s{1,${patternSize}})`),
string: new RegExp(`^(?:[^\"\\\\]{1,${patternSize}}|\\\\[bfnrt\"\\\\\\/]|\\\\u[\\da-fA-F]{4}|\\")`),
key1: new RegExp(`^(?:[\"\\}]|\\s{1,${patternSize}})`),
colon: new RegExp(`^(?:\\:|\\s{1,${patternSize}})`),
comma: new RegExp(`^(?:[\\,\\]\\}]|\\s{1,${patternSize}})`),
ws: new RegExp(`^\\s{1,${patternSize}}`),
numberStart: /^\d/,
numberDigit: new RegExp(`^\\d{0,${patternSize}}`),
numberFraction: /^[\.eE]/,
numberExponent: /^[eE]/,
numberExpSign: /^[-+]/
};

!noSticky &&
Object.keys(patterns).forEach(key => {
let src = patterns[key].source.slice(1); // lop off ^
if (src.slice(0, 3) === '(?:' && src.slice(-1) === ')') {
src = src.slice(3, -1);
}
patterns[key] = new RegExp(src, 'y');
});

patterns.numberFracStart = patterns.numberExpStart = patterns.numberStart;
patterns.numberFracDigit = patterns.numberExpDigit = patterns.numberDigit;
patterns.numberFracStart = patterns.numberExpStart = patterns.numberStart;
patterns.numberFracDigit = patterns.numberExpDigit = patterns.numberDigit;

return patterns;
}

const values = {true: true, false: false, null: null},
expected = {object: 'objectStop', array: 'arrayStop', '': 'done'};
Expand All @@ -55,6 +60,7 @@ class Parser extends Utf8Stream {
super(Object.assign({}, options, {readableObjectMode: true}));

this._packKeys = this._packStrings = this._packNumbers = this._streamKeys = this._streamStrings = this._streamNumbers = true;
this._patternSize = DEFAULT_PATTERN_SIZE;
if (options) {
'packValues' in options && (this._packKeys = this._packStrings = this._packNumbers = options.packValues);
'packKeys' in options && (this._packKeys = options.packKeys);
Expand All @@ -64,6 +70,8 @@ class Parser extends Utf8Stream {
'streamKeys' in options && (this._streamKeys = options.streamKeys);
'streamStrings' in options && (this._streamStrings = options.streamStrings);
'streamNumbers' in options && (this._streamNumbers = options.streamNumbers);
'patternSize' in options && (this._patternSize = options.patternSize);

this._jsonStreaming = options.jsonStreaming;
}
!this._packKeys && (this._streamKeys = true);
Expand All @@ -76,6 +84,8 @@ class Parser extends Utf8Stream {
this._parent = '';
this._open_number = false;
this._accumulator = '';

this._patterns = getPatterns(this._patternSize);
}

_flush(callback) {
Expand Down Expand Up @@ -104,8 +114,8 @@ class Parser extends Utf8Stream {
switch (this._expect) {
case 'value1':
case 'value':
patterns.value1.lastIndex = index;
match = patterns.value1.exec(this._buffer);
this._patterns.value1.lastIndex = index;
match = this._patterns.value1.exec(this._buffer);
if (!match) {
if (this._done || index + MAX_PATTERN_SIZE < this._buffer.length) {
if (index < this._buffer.length) return callback(new Error('Parser cannot parse input: expected a value'));
Expand Down Expand Up @@ -197,8 +207,8 @@ class Parser extends Utf8Stream {
break;
case 'keyVal':
case 'string':
patterns.string.lastIndex = index;
match = patterns.string.exec(this._buffer);
this._patterns.string.lastIndex = index;
match = this._patterns.string.exec(this._buffer);
if (!match) {
if (index < this._buffer.length && (this._done || this._buffer.length - index >= 6))
return callback(new Error('Parser cannot parse input: escaped characters'));
Expand Down Expand Up @@ -246,8 +256,8 @@ class Parser extends Utf8Stream {
break;
case 'key1':
case 'key':
patterns.key1.lastIndex = index;
match = patterns.key1.exec(this._buffer);
this._patterns.key1.lastIndex = index;
match = this._patterns.key1.exec(this._buffer);
if (!match) {
if (index < this._buffer.length || this._done) return callback(new Error('Parser cannot parse input: expected an object key'));
break main; // wait for more input
Expand All @@ -269,8 +279,8 @@ class Parser extends Utf8Stream {
}
break;
case 'colon':
patterns.colon.lastIndex = index;
match = patterns.colon.exec(this._buffer);
this._patterns.colon.lastIndex = index;
match = this._patterns.colon.exec(this._buffer);
if (!match) {
if (index < this._buffer.length || this._done) return callback(new Error("Parser cannot parse input: expected ':'"));
break main; // wait for more input
Expand All @@ -285,8 +295,8 @@ class Parser extends Utf8Stream {
break;
case 'arrayStop':
case 'objectStop':
patterns.comma.lastIndex = index;
match = patterns.comma.exec(this._buffer);
this._patterns.comma.lastIndex = index;
match = this._patterns.comma.exec(this._buffer);
if (!match) {
if (index < this._buffer.length || this._done) return callback(new Error("Parser cannot parse input: expected ','"));
break main; // wait for more input
Expand Down Expand Up @@ -318,8 +328,8 @@ class Parser extends Utf8Stream {
break;
// number chunks
case 'numberStart': // [0-9]
patterns.numberStart.lastIndex = index;
match = patterns.numberStart.exec(this._buffer);
this._patterns.numberStart.lastIndex = index;
match = this._patterns.numberStart.exec(this._buffer);
if (!match) {
if (index < this._buffer.length || this._done) return callback(new Error('Parser cannot parse input: expected a starting digit'));
break main; // wait for more input
Expand All @@ -335,8 +345,8 @@ class Parser extends Utf8Stream {
}
break;
case 'numberDigit': // [0-9]*
patterns.numberDigit.lastIndex = index;
match = patterns.numberDigit.exec(this._buffer);
this._patterns.numberDigit.lastIndex = index;
match = this._patterns.numberDigit.exec(this._buffer);
if (!match) {
if (index < this._buffer.length || this._done) return callback(new Error('Parser cannot parse input: expected a digit'));
break main; // wait for more input
Expand All @@ -363,8 +373,8 @@ class Parser extends Utf8Stream {
}
break;
case 'numberFraction': // [\.eE]?
patterns.numberFraction.lastIndex = index;
match = patterns.numberFraction.exec(this._buffer);
this._patterns.numberFraction.lastIndex = index;
match = this._patterns.numberFraction.exec(this._buffer);
if (!match) {
if (index < this._buffer.length || this._done) {
this._expect = expected[this._parent];
Expand All @@ -383,8 +393,8 @@ class Parser extends Utf8Stream {
}
break;
case 'numberFracStart': // [0-9]
patterns.numberFracStart.lastIndex = index;
match = patterns.numberFracStart.exec(this._buffer);
this._patterns.numberFracStart.lastIndex = index;
match = this._patterns.numberFracStart.exec(this._buffer);
if (!match) {
if (index < this._buffer.length || this._done) return callback(new Error('Parser cannot parse input: expected a fractional part of a number'));
break main; // wait for more input
Expand All @@ -400,8 +410,8 @@ class Parser extends Utf8Stream {
}
break;
case 'numberFracDigit': // [0-9]*
patterns.numberFracDigit.lastIndex = index;
match = patterns.numberFracDigit.exec(this._buffer);
this._patterns.numberFracDigit.lastIndex = index;
match = this._patterns.numberFracDigit.exec(this._buffer);
value = match[0];
if (value) {
this._streamNumbers && this.push({name: 'numberChunk', value: value});
Expand All @@ -424,8 +434,8 @@ class Parser extends Utf8Stream {
}
break;
case 'numberExponent': // [eE]?
patterns.numberExponent.lastIndex = index;
match = patterns.numberExponent.exec(this._buffer);
this._patterns.numberExponent.lastIndex = index;
match = this._patterns.numberExponent.exec(this._buffer);
if (!match) {
if (index < this._buffer.length) {
this._expect = expected[this._parent];
Expand All @@ -448,8 +458,8 @@ class Parser extends Utf8Stream {
}
break;
case 'numberExpSign': // [-+]?
patterns.numberExpSign.lastIndex = index;
match = patterns.numberExpSign.exec(this._buffer);
this._patterns.numberExpSign.lastIndex = index;
match = this._patterns.numberExpSign.exec(this._buffer);
if (!match) {
if (index < this._buffer.length) {
this._expect = 'numberExpStart';
Expand All @@ -469,8 +479,8 @@ class Parser extends Utf8Stream {
}
break;
case 'numberExpStart': // [0-9]
patterns.numberExpStart.lastIndex = index;
match = patterns.numberExpStart.exec(this._buffer);
this._patterns.numberExpStart.lastIndex = index;
match = this._patterns.numberExpStart.exec(this._buffer);
if (!match) {
if (index < this._buffer.length || this._done) return callback(new Error('Parser cannot parse input: expected an exponent part of a number'));
break main; // wait for more input
Expand All @@ -486,8 +496,8 @@ class Parser extends Utf8Stream {
}
break;
case 'numberExpDigit': // [0-9]*
patterns.numberExpDigit.lastIndex = index;
match = patterns.numberExpDigit.exec(this._buffer);
this._patterns.numberExpDigit.lastIndex = index;
match = this._patterns.numberExpDigit.exec(this._buffer);
value = match[0];
if (value) {
this._streamNumbers && this.push({name: 'numberChunk', value: value});
Expand All @@ -506,8 +516,8 @@ class Parser extends Utf8Stream {
}
break;
case 'done':
patterns.ws.lastIndex = index;
match = patterns.ws.exec(this._buffer);
this._patterns.ws.lastIndex = index;
match = this._patterns.ws.exec(this._buffer);
if (!match) {
if (index < this._buffer.length) {
if (this._jsonStreaming) {
Expand Down
50 changes: 50 additions & 0 deletions tests/test_parser.js
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,18 @@ const emit = require('../utils/emit');
const ReadString = require('./ReadString');
const Counter = require('./Counter');

const generateRandomBase64String = (length) => {
const base64Chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

// Generate the random string
let result = '';
for (let i = 0; i < length; i++) {
result += base64Chars.charAt(Math.floor(Math.random() * base64Chars.length));
}

return result;
};

const survivesRoundtrip = (t, object) => {
const async = t.startAsync('survivesRoundtrip: ' + object);

Expand Down Expand Up @@ -375,5 +387,43 @@ unit.add(module, [
eval(t.ASSERT('result.length === 0'));
async.done();
});
},
function test_parser_long_string_default_pattern_size(t) {
const string = generateRandomBase64String(1000000);
const async = t.startAsync('test_parser_long_string_default_pattern_size');

const input = string,
pipeline = new ReadString(JSON.stringify(input)).pipe(
new Parser({packStrings: false})
),
result = [];

pipeline.on('data', function (chunk) {
result.push({name: chunk.name, val: chunk.value});
});
pipeline.on('end', function () {
// 3909 taken from test run
eval(t.ASSERT('result.length === 3909'));
async.done();
});
},
function test_parser_long_string_long_pattern_size(t) {
const string = generateRandomBase64String(1000000);
const async = t.startAsync('test_parser_long_string_long_pattern_size');

const input = string,
pipeline = new ReadString(JSON.stringify(input)).pipe(
new Parser({packStrings: false, patternSize: 10000})
),
result = [];

pipeline.on('data', function (chunk) {
result.push({name: chunk.name, val: chunk.value});
});
pipeline.on('end', function () {
// 100 = startString + 100 x stringChunk + endString
eval(t.ASSERT('result.length === 102'));
async.done();
});
}
]);