Highlighter

Highlighter is a regular expression based syntax highlighter library written in Scala. Highlighter is inspired by Pygments, and it is not difficult to port Pygments lexers to Highlighter. Highlighter has a convenient definition language to make it easier to develop new highlighters.

Examples

Highlighter Definition

Here's an example of a typical Highlighter definition and the result of applying it to a small HTML document. This definition is a port of the Pygments HTML Lexer which includes CSS highlighting for style elements.

Definition

highlighter
  name: HTML
options
  regex: dotall ignorecase
templates
  default: {{ <span class="\class">\escape\text</span> }}
states
  root:
    &\S*?;                        => Name.Entity
    \<\!\[CDATA\[.*?\]\]\>        => Comment.Preproc
    <!--                          => Comment >comment
    <\?.*?\?>                     => Comment.Preproc
    <![^>]*>                      => Comment.Preproc
    (<)\s*(script)\s*             => (Punctuation Name.Tag) >script-content >tag
    (<)\s*(style)\s*              => (Punctuation Name.Tag) >style-content >tag
    (<)\s*([\w:.-]+)              => (Punctuation Name.Tag) >tag
    (<)\s*(/)\s*([\w:.-]+)\s*(>)  => (Punctuation Punctuation Name.Tag Punctuation)
  comment:
    [^-]+  => Comment
    -->    => Comment ^
    -      => Comment
  tag:
    ([\w:-]+)\s*(=)\s*  => (Name.Attribute Operator) >attr
    [\w:-]+             => Name.Attribute
    (/?)\s*(>)          => (Punctuation Punctuation) ^
  script-content:
    (<)\s*(/)\s*(script)\s*(>)  => (Punctuation Punctuation Name.Tag Punctuation) ^
    .+?(?=<\s*/\s*script\s*>)   => [javascript]
  style-content:
    (<)\s*(/)\s*(style)\s*(>)  => (Punctuation Punctuation Name.Tag Punctuation) ^
    .+?(?=<\s*/\s*style\s*>)   => [css]
  attr:
    ".*?"    => String ^
    '.*?'    => String ^
    [^\s>]+  => String ^

Input

<!DOCTYPE html>
<html>
  <head>
    <style>
      body {background-color: powderblue;}
      p    {color: red;}
    </style>
  </head>
  <body>
    <!-- comment -->
    <p align="right">&lt;paragraph&gt;</p>
  </body>
</html>

Output

The styling that was used for the highlighting was Pygments "friendly" theme.

Usage

Library

Use the following definition to use Highlighter in your Maven project:

<repository>
  <id>hyperreal</id>
  <url>https://dl.bintray.com/edadma/maven</url>
</repository>

<dependency>
  <groupId>io.github.edadma</groupId>
  <artifactId>highlighter</artifactId>
  <version>0.1.7</version>
</dependency>

Add the following to your build.sbt file to use Highlighter in your SBT project:

resolvers += "Hyperreal Repository" at "https://dl.bintray.com/edadma/maven"

libraryDependencies += "io.github.edadma" %% "highlighter" % "0.1.0"

Executable

An executable can be downloaded from here. You do not need the Scala library for it to work because the JAR already contains all dependencies. You just need Java 8+ installed.

Run it as a normal Java executable JAR with the command java -jar highlighter-0.1.7.jar <definition>... [<input>] in the folder where you downloaded the file, where definition is the name of the highlighter definition file, and is the file containing the code to be highlighted. If multiple definition files are given, the first one is used for highlighting and the others are passed to it as dependencies.

Building

Requirements

Java 8
SBT 1.1.5+
Scala 2.12.6+

Clone and Assemble Executable

git clone git://github.com/edadma/highlighter.git
cd highlighter
sbt assembly

The command sbt assembly also runs all the unit tests.

edadma / highlighter 0.1.7