Initial commit

.editorconfig

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+root = true
+
+[*.cr]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+trim_trailing_whitespace = true

.gitignore

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+/docs/
+/lib/
+/bin/
+/.shards/
+*.dwarf
+
+# Libraries don't need dependency lock
+# Dependencies will be locked in application that uses them
+/shard.lock

.travis.yml

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+language: crystal

LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2018 Omar Roth
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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+# syntax
+[![GitHub release](https://img.shields.io/github/release/omarroth/syntax.cr.svg)](https://github.com/omarroth/syntax.cr/releases)
+
+> This is a project built with [marpa](https://github.com/omarroth/marpa).
+
+Flexible syntax highlighter.
+
+## Installation
+
+Add this to your application's `shard.yml`:
+
+```yaml
+dependencies:
+  syntax:
+    github: omarroth/syntax.cr
+```
+
+## Usage
+
+```crystal
+require "syntax"
+
+highlighter = Syntax::Highlighter.new
+grammar = <<-'END_BNF'
+# Grammar from https://metacpan.org/pod/distribution/Marpa-R2/pod/Semantics.pod
+:start ::= Expression
+Expression ::= Number
+| '(' Expression ')' bgcolor => salmon
+|| Expression '**' Expression bgcolor => red
+|| Expression '*' Expression bgcolor => yellow color => black
+| Expression '/' Expression bgcolor => green color => orange
+|| Expression '+' Expression bgcolor => blue color => orange
+| Expression '-' Expression bgcolor => cyan color => black
+
+Number ~ [\d]+
+
+:discard ~ whitespace
+whitespace ~ [\s]+
+END_BNF
+
+input = "10 + (6 - 1 / 3) * 2"
+
+highlighter.highlight(input, grammar)
+```
+
+## Contributing
+
+1. Fork it (<https://github.com/omarroth/syntax.cr/fork>)
+2. Create your feature branch (`git checkout -b my-new-feature`)
+3. Commit your changes (`git commit -am 'Add some feature'`)
+4. Push to the branch (`git push origin my-new-feature`)
+5. Create a new Pull Request
+
+## Contributors
+
+- [omarroth](https://github.com/omarroth) Omar Roth - creator, maintainer

shard.yml

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+name: syntax
+version: 0.1.0
+
+authors:
+  - Omar Roth <[email protected]>
+
+crystal: 0.25.0
+
+dependencies:
+  marpa:
+    github: omarroth/marpa
+    branch: master
+
+license: MIT

spec/spec_helper.cr

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+require "spec"
+require "../src/syntax"

spec/syntax.cr_spec.cr

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+require "./spec_helper"
+
+describe Syntax do
+  # TODO: Write tests
+
+  it "highlights text" do
+    highlighter = Syntax::Highlighter.new
+
+    grammar = <<-'END_BNF'
+    :start ::= S
+    S ::= 'a' color => green
+    END_BNF
+
+    highlighter.highlight("a", grammar).should eq %(<span class="code" style="background-color:inherit; color:#008000">a</span>)
+  end
+end

src/syntax.cr

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+require "./syntax/*"
+require "marpa"
+
+module Syntax
+  class Highlighter
+    def highlight(input : String, input_grammar : String)
+      parser = Marpa::Parser.new
+
+      spec = Marpa::Builder.new
+      spec = build_spec(spec)
+      # spec = File.read("src/syntax/spec.bnf")
+      # meta_grammar = parser.compile(meta_grammar)
+
+      grammar = Grammar.new
+      parser.parse(input_grammar, spec, actions: grammar)
+      rules = grammar.rules
+
+      actions = Actions.new(rules)
+      events = Events.new(input)
+      stack = parser.parse(input, grammar, actions: actions, events: events)
+      stack = stack.as(Array).flatten
+
+      parser.values.to_a.reverse.each_with_index do |values, i|
+        key, value = values
+        key = key.abs
+
+        input = input.sub(key..(key + value.size - 1), stack[stack.size - i - 1])
+      end
+
+      return input
+    end
+  end
+
+  class Events < Marpa::Events
+    property input
+
+    def initialize(input : String)
+      @input = input
+    end
+
+    def default(context)
+      if context.matches.empty? && context.discards.empty?
+        context.expected.each do |expected|
+          context.matches << {"", expected}
+        end
+      end
+    end
+  end
+
+  class Actions < Marpa::Actions
+    property rules
+
+    def initialize(rules : Hash(Int32, Hash(String, String)))
+      @rules = rules
+    end
+
+    def perform_color(context, rule_id)
+      rule = @rules[rule_id]
+
+      bgcolor = rule["bgcolor"]?
+      bgcolor ||= "inherit"
+
+      color = rule["color"]?
+      color ||= "inherit"
+
+      span = %(<span class="code" style="background-color:#{bgcolor}; color:#{color}">)
+      end_span = "</span>"
+
+      body = context.as(Array)
+      body = body.flatten
+
+      context.clear
+
+      body[0] = span + body[0]
+      body[-1] = body[-1] + end_span
+      body.each do |element|
+        context << element
+      end
+
+      context
+    end
+  end
+
+  class Grammar < Marpa::Builder
+    def adverb_list(context)
+      adverbs = context.dup
+      adverbs = adverbs.as(Array)
+      context.clear
+
+      adverbs.each do |adverb|
+        adverb = adverb[0].as(Array)
+
+        case adverb[0]
+        when "color", "bgcolor"
+          context << adverb
+          context << ["action", "=>", "perform_color"]
+        when "action"
+        else
+          context << adverb
+        end
+      end
+
+      context
+    end
+
+    def css_color(context)
+      colors = {
+        "aliceblue"            => "#F0F8FF",
+        "antiquewhite"         => "#FAEBD7",
+        "aqua"                 => "#00FFFF",
+        "aquamarine"           => "#7FFFD4",
+        "azure"                => "#F0FFFF",
+        "beige"                => "#F5F5DC",
+        "bisque"               => "#FFE4C4",
+        "black"                => "#000000",
+        "blanchedalmond"       => "#FFEBCD",
+        "blue"                 => "#0000FF",
+        "blueviolet"           => "#8A2BE2",
+        "brown"                => "#A52A2A",
+        "burlywood"            => "#DEB887",
+        "cadetblue"            => "#5F9EA0",
+        "chartreuse"           => "#7FFF00",
+        "chocolate"            => "#D2691E",
+        "coral"                => "#FF7F50",
+        "cornflowerblue"       => "#6495ED",
+        "cornsilk"             => "#FFF8DC",
+        "crimson"              => "#DC143C",
+        "cyan"                 => "#00FFFF",
+        "darkblue"             => "#00008B",
+        "darkcyan"             => "#008B8B",
+        "darkgoldenrod"        => "#B8860B",
+        "darkgray"             => "#A9A9A9",
+        "darkgreen"            => "#006400",
+        "darkgrey"             => "#A9A9A9",
+        "darkkhaki"            => "#BDB76B",
+        "darkmagenta"          => "#8B008B",
+        "darkolivegreen"       => "#556B2F",
+        "darkorange"           => "#FF8C00",
+        "darkorchid"           => "#9932CC",
+        "darkred"              => "#8B0000",
+        "darksalmon"           => "#E9967A",
+        "darkseagreen"         => "#8FBC8F",
+        "darkslateblue"        => "#483D8B",
+        "darkslategray"        => "#2F4F4F",
+        "darkslategrey"        => "#2F4F4F",
+        "darkturquoise"        => "#00CED1",
+        "darkviolet"           => "#9400D3",
+        "deeppink"             => "#FF1493",
+        "deepskyblue"          => "#00BFFF",
+        "dimgray"              => "#696969",
+        "dimgrey"              => "#696969",
+        "dodgerblue"           => "#1E90FF",
+        "firebrick"            => "#B22222",
+        "floralwhite"          => "#FFFAF0",
+        "forestgreen"          => "#228B22",
+        "fuchsia"              => "#FF00FF",
+        "gainsboro"            => "#DCDCDC",
+        "ghostwhite"           => "#F8F8FF",
+        "gold"                 => "#FFD700",
+        "goldenrod"            => "#DAA520",
+        "gray"                 => "#808080",
+        "green"                => "#008000",
+        "greenyellow"          => "#ADFF2F",
+        "grey"                 => "#808080",
+        "honeydew"             => "#F0FFF0",
+        "hotpink"              => "#FF69B4",
+        "indianred"            => "#CD5C5C",
+        "indigo"               => "#4B0082",
+        "ivory"                => "#FFFFF0",
+        "khaki"                => "#F0E68C",
+        "lavender"             => "#E6E6FA",
+        "lavenderblush"        => "#FFF0F5",
+        "lawngreen"            => "#7CFC00",
+        "lemonchiffon"         => "#FFFACD",
+        "lightblue"            => "#ADD8E6",
+        "lightcoral"           => "#F08080",
+        "lightcyan"            => "#E0FFFF",
+        "lightgoldenrodyellow" => "#FAFAD2",
+        "lightgray"            => "#D3D3D3",
+        "lightgreen"           => "#90EE90",
+        "lightgrey"            => "#D3D3D3",
+        "lightpink"            => "#FFB6C1",
+        "lightsalmon"          => "#FFA07A",
+        "lightseagreen"        => "#20B2AA",
+        "lightskyblue"         => "#87CEFA",
+        "lightslategray"       => "#778899",
+        "lightslategrey"       => "#778899",
+        "lightsteelblue"       => "#B0C4DE",
+        "lightyellow"          => "#FFFFE0",
+        "lime"                 => "#00FF00",
+        "limegreen"            => "#32CD32",
+        "linen"                => "#FAF0E6",
+        "magenta"              => "#FF00FF",
+        "maroon"               => "#800000",
+        "mediumaquamarine"     => "#66CDAA",
+        "mediumblue"           => "#0000CD",
+        "mediumorchid"         => "#BA55D3",
+        "mediumpurple"         => "#9370DB",
+        "mediumseagreen"       => "#3CB371",
+        "mediumslateblue"      => "#7B68EE",
+        "mediumspringgreen"    => "#00FA9A",
+        "mediumturquoise"      => "#48D1CC",
+        "mediumvioletred"      => "#C71585",
+        "midnightblue"         => "#191970",
+        "mintcream"            => "#F5FFFA",
+        "mistyrose"            => "#FFE4E1",
+        "moccasin"             => "#FFE4B5",
+        "navajowhite"          => "#FFDEAD",
+        "navy"                 => "#000080",
+        "oldlace"              => "#FDF5E6",
+        "olive"                => "#808000",
+        "olivedrab"            => "#6B8E23",
+        "orange"               => "#FFA500",
+        "orangered"            => "#FF4500",
+        "orchid"               => "#DA70D6",
+        "palegoldenrod"        => "#EEE8AA",
+        "palegreen"            => "#98FB98",
+        "paleturquoise"        => "#AFEEEE",
+        "palevioletred"        => "#DB7093",
+        "papayawhip"           => "#FFEFD5",
+        "peachpuff"            => "#FFDAB9",
+        "peru"                 => "#CD853F",
+        "pink"                 => "#FFC0CB",
+        "plum"                 => "#DDA0DD",
+        "powderblue"           => "#B0E0E6",
+        "purple"               => "#800080",
+        "rebeccapurple"        => "#663399",
+        "red"                  => "#FF0000",
+        "rosybrown"            => "#BC8F8F",
+        "royalblue"            => "#4169E1",
+        "saddlebrown"          => "#8B4513",
+        "salmon"               => "#FA8072",
+        "sandybrown"           => "#F4A460",
+        "seagreen"             => "#2E8B57",
+        "seashell"             => "#FFF5EE",
+        "sienna"               => "#A0522D",
+        "silver"               => "#C0C0C0",
+        "skyblue"              => "#87CEEB",
+        "slateblue"            => "#6A5ACD",
+        "slategray"            => "#708090",
+        "slategrey"            => "#708090",
+        "snow"                 => "#FFFAFA",
+        "springgreen"          => "#00FF7F",
+        "steelblue"            => "#4682B4",
+        "tan"                  => "#D2B48C",
+        "teal"                 => "#008080",
+        "thistle"              => "#D8BFD8",
+        "tomato"               => "#FF6347",
+        "turquoise"            => "#40E0D0",
+        "violet"               => "#EE82EE",
+        "wheat"                => "#F5DEB3",
+        "white"                => "#FFFFFF",
+        "whitesmoke"           => "#F5F5F5",
+        "yellow"               => "#FFFF00",
+        "yellowgreen"          => "#9ACD32",
+      }
+
+      context[0] = colors[context[0].as(String).downcase]
+    end
+  end
+end