pattern-replace

Replace text patterns with a given replacement.

Install

First make sure you have installed the latest version of node.js (You may need to restart your computer after this step).

From NPM for use as a command line app:

npm install pattern-replace -g

From NPM for programmatic use:

npm install pattern-replace

From Git:

git clone git://github.com/outaTiME/pattern-replace
cd pattern-replace
npm link .

API Reference

Assuming installation via NPM, you can use pattern-replace in your application like this:

var fs = require('fs');
var Replacer = require('pattern-replace');
var options = {
  patterns: [
    {
      match: 'foo',
      replacement: 'bar'
    }
  ]
};
var replacer = new Replacer(options);
var contents = '@@foo';
var result = replacer.replace(contents);
console.log(result); // bar

Replacer Options

patterns

Type: Array

Define patterns that will be used to replace the contents of source files.

patterns.match

Type: String|RegExp

Indicates the matching expression.

If matching type is String and expression attribute is false we use a simple variable lookup mechanism @@string (in any other case we use the default regexp replace logic):

{
  patterns: [
    {
      match: 'foo',
      replacement: 'bar', // replaces "@@foo" to "bar"
      expression: false   // simple variable lookup
    }
  ]
}

patterns.replacement

Type: String|Function|Object

Indicates the replacement for match, for more information about replacement check out the String.replace.

You can specify a function as replacement. In this case, the function will be invoked after the match has been performed. The function's result (return value) will be used as the replacement string.

{
  patterns: [
    {
      match: /foo/g,
      replacement: function () {
        return 'bar'; // replaces "foo" to "bar"
      }
    }
  ]
}

Also supports object as replacement (we create string representation of object using JSON.stringify):

{
  patterns: [
    {
      match: /foo/g,
      replacement: [1, 2, 3] // replaces "foo" with string representation of "array" object
    }
  ]
}

patterns.json

Type: Object

If an attribute json found in pattern definition we flatten the object using delimiter concatenation and each key–value pair will be used for the replacement (simple variable lookup mechanism and no regexp support).

{
  patterns: [
    {
      json: {
        "key": "value" // replaces "@@key" to "value"
      }
    }
  ]
}

Also supports nested objects:

{
  patterns: [
    {
      json: {
        "key": "value",   // replaces "@@key" to "value"
        "inner": {        // replaces "@@inner" with string representation of "inner" object
          "key": "value"  // replaces "@@inner.key" to "value"
        }
      }
    }
  ]
}

patterns.yaml

Type: String

If an attribute yaml found in pattern definition we flatten the object using delimiter concatenation and each key–value pair will be used for the replacement (simple variable lookup mechanism and no regexp support).

{
  patterns: [
    {
      yaml: 'key: value'  // replaces "@@key" to "value"
    }
  ]
}

patterns.expression

Type: Boolean Default: false

Indicates the type of matching.

If detects regexp instance in match attribute, we assume to works with expression matcher (in any other case should be forced).

variables

Type: Object

This is the old way to define patterns using plain object (simple variable lookup mechanism and no regexp support), you can still using but for more control you should use the new patterns way.

{
  variables: {
    'key': 'value' // replaces "@@key" to "value"
  }
}

prefix

Type: String Default: @@

The prefix added for matching (prevent bad replacements / easy way).

This only applies for simple variable lookup mechanism.

usePrefix

Type: Boolean Default: true

If set to false, we match the pattern without prefix concatenation (useful when you want to lookup an simple string).

This only applies for simple variable lookup mechanism.

preservePrefix

Type: Boolean Default: false

If set to true, we preserve the prefix in target.

This only applies for simple variable lookup mechanism and patterns.replacement is an string.

delimiter

Type: String Default: .

The delimiter used to flatten when using object as replacement.

preserveOrder

Type: Boolean Default: false

If set to true, we preserve the patterns definition order, otherwise these will be sorted (in ascending order) to prevent replacement issues like head / header (typo regexps will be resolved at last).

Usage Examples

Basic

File src/manifest.appcache:

CACHE MANIFEST
# @@timestamp

CACHE:

favicon.ico
index.html

NETWORK:
*

Node:

var fs = require('fs');
var Replacer = require('pattern-replace');
var options = {
  patterns: [
    {
      match: 'timestamp',
      replacement: new Date().getTime()
    }
  ]
};
var replacer = new Replacer(options);
var contents = fs.readFileSync('./src/manifest.appcache').toString();
var result = replacer.replace(contents);
console.log(result); // replaced output

Multiple matching

File src/manifest.appcache:

CACHE MANIFEST
# @@timestamp

CACHE:

favicon.ico
index.html

NETWORK:
*

File src/humans.txt:

              __     _
   _    _/__  /./|,//_`
  /_//_// /_|///  //_, outaTiME v.@@version

/* TEAM */
  Web Developer / Graphic Designer: Ariel Oscar Falduto
  Site: http://www.outa.im
  Twitter: @outa7iME
  Contact: afalduto at gmail dot com
  From: Buenos Aires, Argentina

/* SITE */
  Last update: @@timestamp
  Standards: HTML5, CSS3, robotstxt.org, humanstxt.org
  Components: H5BP, Modernizr, jQuery, Twitter Bootstrap, LESS, Jade, Grunt
  Software: Sublime Text 2, Photoshop, LiveReload

Node:

var fs = require('fs');
var Replacer = require('pattern-replace');
var options = {
  patterns: [
    {
      match: 'version',
      replacement: '0.1.0'
    },
    {
      match: 'timestamp',
      replacement: new Date().getTime()
    }
  ]
};
var replacer = new Replacer(options);
var contents = fs.readFileSync('./src/manifest.appcache').toString();
var result = replacer.replace(contents);
console.log(result); // replaced output
contents = fs.readFileSync('./src/humans.txt').toString();
result = replacer.replace(contents);
console.log(result); // replaced output

Cache busting

File src/index.html:

<head>
  <link rel="stylesheet" href="/css/style.css?rel=@@timestamp">
  <script src="/js/app.js?rel=@@timestamp"></script>
</head>

Node:

var fs = require('fs');
var Replacer = require('pattern-replace');
var options = {
  patterns: [
    {
      match: 'timestamp',
      replacement: new Date().getTime()
    }
  ]
};
var replacer = new Replacer(options);
var contents = fs.readFileSync('./src/index.html').toString();
var result = replacer.replace(contents);
console.log(result); // replaced output

Include file

File src/index.html:

<body>
  @@include
</body>

Node:

var fs = require('fs');
var Replacer = require('pattern-replace');
var options = {
  patterns: [
    {
      match: 'include',
      replacement: fs.readFileSync('./includes/content.html').toString()
    }
  ]
};
var replacer = new Replacer(options);
var contents = fs.readFileSync('./src/index.html').toString();
var result = replacer.replace(contents);
console.log(result); // replaced output

Regular expression

File src/username.txt:

John Smith

Node:

var fs = require('fs');
var Replacer = require('pattern-replace');
var options = {
  patterns: [
    {
      match: /(\w+)\s(\w+)/,
      replacement: '$2, $1' // replaces "John Smith" to "Smith, John"
    }
  ]
};
var replacer = new Replacer(options);
var contents = fs.readFileSync('./username.txt').toString();
var result = replacer.replace(contents);
console.log(result); // replaced output

Lookup for foo instead of @@foo

The String matching type or expression in false generates a simple variable lookup mechanism @@string, to skip this mode use one of the below rules ... make your choice:

Node:

var Replacer = require('pattern-replace');

// option 1 (explicitly using an regexp)
var replacer_op1 = new Replacer({
  patterns: [
    {
      match: /foo/g,
      replacement: 'bar'
    }
  ]
});

// option 2 (easy way)
var replacer_op2 = new Replacer({
  patterns: [
    {
      match: 'foo',
      replacement: 'bar'
    }
  ],
  usePrefix: false
});

// option 3 (old way)
var replacer_op3 = new Replacer({
  patterns: [
    {
      match: 'foo',
      replacement: 'bar'
    }
  ],
  prefix: '' // remove prefix
});

Command Line

(Coming soon)

Release History

• 2014-03-12   v0.1.2   New pattern matching for YAML object. New preserveOrder flag.
• 2014-02-26   v0.1.1   Remove the force flag (only applies in grunt plugin).
• 2014-02-25   v0.1.0   Initial version.

Task submitted by Ariel Falduto