Add Solidity lexer (#760)

This commit adds a lexer for Solidity.

lib/rouge/demos/solidity

@@ -0,0 +1,13 @@
+pragma solidity ~0.4.15;
+
+interface IMirror {
+    function reflect() external payable returns(bool /* ain't I pretty?.. */);
+}
+
+contract Mirror is IMirror {
+    event logMessage(address indexed sender, uint256 value, uint256 gas, bytes data);
+
+    function () { // no funny stuff
+       revert();
+    }
+}

lib/rouge/lexers/solidity.rb

@@ -0,0 +1,185 @@
+# -*- coding: utf-8 -*- #
+
+module Rouge
+  module Lexers
+    class Solidity < RegexLexer
+      title "Solidity"
+      desc "Solidity, an Ethereum smart contract programming language"
+      tag 'solidity'
+      filenames '*.sol', '*.solidity'
+      mimetypes 'text/x-solidity'
+
+      # optional comment or whitespace
+      ws = %r((?:\s|//.*?\n|/[*].*?[*]/)+)
+      id = /[a-zA-Z$_][\w$_]*/
+
+      def self.detect?(text)
+        return true if text.start_with? 'pragma solidity'
+      end
+
+      # TODO: seperate by "type"
+      def self.keywords
+        @keywords ||= Set.new %w(
+          abstract anonymous as assembly break catch calldata constant
+          constructor continue contract do delete else emit enum event
+          external fallback for function hex if indexed interface
+          internal import is library mapping memory modifier new
+          override payable public pure pragma private receive return
+          returns storage struct throw try type using var view virtual
+          while
+        )
+      end
+
+      def self.builtins
+        return @builtins if @builtins
+
+        @builtins = Set.new %w(
+          now
+          false true
+          balance now selector super this
+          blockhash gasleft
+          assert require revert
+          selfdestruct suicide
+          call callcode delegatecall
+          send transfer
+          addmod ecrecover keccak256 mulmod sha256 sha3 ripemd160
+        )
+
+        # TODO: use (currently shadowed by catch-all in :statements)
+        abi = %w(decode encode encodePacked encodeWithSelector encodeWithSignature)
+        @builtins.merge( abi.map { |i| "abi.#{i}" } )
+        block = %w(coinbase difficulty gaslimit hash number timestamp)
+        @builtins.merge( block.map { |i| "block.#{i}" } )
+        msg = %w(data gas sender sig value)
+        @builtins.merge( msg.map { |i| "msg.#{i}" } )
+        tx = %w(gasprice origin)
+        @builtins.merge( tx.map { |i| "tx.#{i}" } )
+      end
+
+      def self.constants
+        @constants ||= Set.new %w(
+          wei finney szabo ether
+          seconds minutes hours days weeks years
+        )
+      end
+
+      def self.keywords_type
+        @keywords_type ||= Set.new %w(
+          address bool byte bytes int string uint
+        )
+      end
+
+      def self.reserved
+        @reserved ||= Set.new %w(
+          alias after apply auto case copyof default define final fixed
+          immutable implements in inline let macro match mutable null of
+          partial promise reference relocatable sealed sizeof static
+          supports switch typedef typeof ufixed unchecked
+        )
+      end
+
+      start { push :bol }
+
+      state :expr_bol do
+        mixin :inline_whitespace
+
+        rule(//) { pop! }
+      end
+
+      # :expr_bol is the same as :bol but without labels, since
+      # labels can only appear at the beginning of a statement.
+      state :bol do
+        mixin :expr_bol
+      end
+
+      # TODO: natspec in comments
+      state :inline_whitespace do
+        rule %r/[ \t\r]+/, Text
+        rule %r/\\\n/, Text # line continuation
+        rule %r(/\*), Comment::Multiline, :comment_multi
+      end
+
+      state :whitespace do
+        rule %r/\n+/m, Text, :bol
+        rule %r(//(\\.|.)*?\n), Comment::Single, :bol
+        mixin :inline_whitespace
+      end
+
+      state :expr_whitespace do
+        rule %r/\n+/m, Text, :expr_bol
+        mixin :whitespace
+      end
+
+      state :statements do
+        mixin :whitespace
+        rule %r/(hex)?\"/, Str, :string_double
+        rule %r/(hex)?\'/, Str, :string_single
+        rule %r('(\\.|\\[0-7]{1,3}|\\x[a-f0-9]{1,2}|[^\\'\n])')i, Str::Char
+        rule %r/\d\d*\.\d+([eE]\d+)?/i, Num::Float
+        rule %r/0x[0-9a-f]+/i, Num::Hex
+        rule %r/\d+([eE]\d+)?/i, Num::Integer
+        rule %r(\*/), Error
+        rule %r([~!%^&*+=\|?:<>/-]), Operator
+        rule %r/[()\[\],.]/, Punctuation
+        rule %r/u?fixed\d+x\d+/, Keyword::Reserved
+        rule %r/bytes\d+/, Keyword::Type
+        rule %r/u?int\d+/, Keyword::Type
+        rule id do |m|
+          name = m[0]
+
+          if self.class.keywords.include? name
+            token Keyword
+          elsif self.class.builtins.include? name
+            token Name::Builtin
+          elsif self.class.constants.include? name
+            token Keyword::Constant
+          elsif self.class.keywords_type.include? name
+            token Keyword::Type
+          elsif self.class.reserved.include? name
+            token Keyword::Reserved
+          else
+            token Name
+          end
+        end
+      end
+
+      state :root do
+        mixin :expr_whitespace
+        rule(//) { push :statement }
+        # TODO: function declarations
+      end
+
+      state :statement do
+        rule %r/;/, Punctuation, :pop!
+        mixin :expr_whitespace
+        mixin :statements
+        rule %r/[{}]/, Punctuation
+      end
+
+      state :string_common do
+        rule %r/\\(u[a-fA-F0-9]{4}|x..|[^x])/, Str::Escape
+        rule %r/[^\\\"\'\n]+/, Str
+        rule %r/\\\n/, Str # line continuation
+        rule %r/\\/, Str # stray backslash
+      end
+
+      state :string_double do
+        mixin :string_common
+        rule %r/\"/, Str, :pop!
+        rule %r/\'/, Str
+      end
+
+      state :string_single do
+        mixin :string_common
+        rule %r/\'/, Str, :pop!
+        rule %r/\"/, Str
+      end
+
+       state :comment_multi do
+         rule %r(\*/), Comment::Multiline, :pop!
+         rule %r([^*/]+), Comment::Multiline
+         rule %r([*/]), Comment::Multiline
+       end
+    end
+  end
+end

spec/lexers/solidity_spec.rb

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*- #
+
+describe Rouge::Lexers::Solidity do
+  let(:subject) { Rouge::Lexers::Solidity.new }
+
+  describe 'guessing' do
+    include Support::Guessing
+
+    it 'guesses by filename' do
+      assert_guess :filename => 'foo.sol'
+      assert_guess :filename => 'foo.solidity'
+    end
+
+    it 'guesses by mimetype' do
+      assert_guess :mimetype => 'text/x-solidity'
+    end
+
+    it 'guesses by source' do
+      assert_guess :source => 'pragma solidity'
+    end
+  end
+end