StringReader

Reads string based on regular expression that represents delimiter.

const StringReader = require('string-reader')
var reader = new StringReader('The quick brown fox jumps over the lazy dog.');
var words = [];
while(!reader.end){
   words.push(reader.readTo(/\s+|\./));
}
console.log(words);
// [ "The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog" ]

Install

npm install --save string-reader

Constructor

const StringReader = require('string-reader');
var reader = new StringReader(content);

Specify content to read. This argument is passed to content property. (content property)

Methods

readTo(delimiter, holdDelimiter, errorThrown)

Reads from the current position to the specified delimiter.

• delimiter: Specify delimiter as RegExp. When String is specified, it is treated as pattern of RegExp. For example, readTo(';') is equivalent to readTo(new RegExp(';')).
• holdDelimiter: Set true to include matched delimiter into returned string. By default, delimiter does not be included. For example, new StringReader('a:b').readTo(/:/) only returnes a, but new StringReader('a:b').readTo(/:/, true) returns a: including delimiter.
• errorThrown: Specify error that will be thrown if there are no delimiter matched. By default, no error be thrown if delimiter is unmatched, just only reads to end.

Returned value can be treated as String object, but has some additional properties:

• position: Position of the first character of its returned string.
• delimiter: Returned value of RegExp.exec method. Can use this property to detect which delimiter is matchd.
• reader: Instance of StringReader

Note:

• Returned value is extended class that is inherited from String object. Therefore new StringReader('abc;def').readTo(/;/) == 'abc' is true, but new StringReader('abc;def').readTo(/;/) === 'abc' is false. Can call toString method to get primitive String object to prevent such a harmful side effect.
• delimiter never be a pattern that matches empty string. For example, /$/m does not match CR and LF, therefore position will be set before CR and LF and cannot advance to next line. So the following code will be loop: while (!reader.end) reader.readTo(/$/m). For that reason, throws error if empty match is appeared. Use alternatively readTo(/\r?\n|\r/) or readLine() to read to end of the line.

readLine(errorThrown)

Reads from the current position to end of the current line. The next three newline formats are supported: CRLF(Windows), LF(Linux/Mac X and later) and CR(Mac 9 and ealier)

• errorThrown: Specify error that be thrown if the current position is end of string. By default, no error be thrown, just only returns empty string.

readToEnd(errorThrown)

Reads from the current position to the end of string.

• errorThrown: Specify error that be thrown if the current position is end of string. By default, no error be thrown, just only returns empty string.

read(count, errorThrown)

Reads specified-count characters from the current position.

• count: Count to read. Can specify negative value to read backwards.
• errorThrown: Specify error that be thrown when the current position reached out of the string. By default, no error be thrown, just only return empty or partial string.

peekTo(errorThrown), peekLine(errorThrown), peekToEnd(errorThrown), and peek(count, errorThrown)

• peekTo is equivalent to readTo but does not change current position.
• peekLine is equivalent to readLine but does not change current position.
• peekToEnd is equivalent to readToEnd but does not change current position.
• peek is equivalent to read but does not change current position.

push(), pop(holdPosition) [experimental]

push and pop can save/restore position to/from built-in stack, pop returns substring between last pushed index and current index.

• holdPosition: Specify true if do not want to restore by last pushed index.

const StringReader = require('string-reader')
var reader = new StringReader('The quick brown fox jumps over the lazy dog.');
reader.readTo(/\s+/);
console.log(reader.position);
// 4
reader.push();
reader.readTo(/\s+/);
reader.readTo(/\s+/);
reader.readTo(/\s+/);
console.log(reader.pop());
// quick brown fox
console.log(reader.position);
// 4

Properties

content

Get or set the original string.

NOTE:

• If set some value, position is always reset to zero.
• If set null or undefined, empty string is alternatively set.
• If set non-string object, return-value of its toString is alternatively set.

position

Get or set current position.

NOTE:

• If set value that is smaller than zero, zero is alternatively set.
• If set value that is greather than its length, value of length is alternatively set.

length (Readonly)

Returns total length of original string.

end (Readonly)

Returns whether its position is end of string.

License

Distributed under the MIT license.

Copyright (C) 2016 Retorillo