Add Lua scanner

rubychan · Quintus · Apr 21, 2012 · Apr 21, 2012 · Apr 21, 2012 · Apr 22, 2012
commit 9f568d9a82b2df68c814a0830ba725f563477a3b
diff --git a/lib/coderay/scanners/lua.rb b/lib/coderay/scanners/lua.rb
@@ -0,0 +1,137 @@
+# -*- coding: utf-8 -*-
+
+# http://www.lua.org/manual/5.2/manual.html
+class CodeRay::Scanners::Lua < CodeRay::Scanners::Scanner
+
+  register_for :lua
+  file_extension "lua"
+  title "Lua"
+
+  KEYWORDS = %w[and break do else elseif end
+  for function goto if in
+  local not or repeat return
+  then until while
+  ]
+
+  PREDEFINED_CONSTANTS = %w[false true nil]
+
+  IDENT_KIND = CodeRay::WordList.new(:ident)
+    .add(KEYWORDS, :keyword)
+    .add(PREDEFINED_CONSTANTS, :predefined_constant)
+
+  protected
+
+  def setup
+    @state = :initial
+  end
+
+  def scan_tokens(encoder, options)
+    @encoder = encoder
+    @options = options
+
+    send(:"handle_state_#@state") until eos?
+
+
+    @encoder
+  end
+
+  def handle_state_initial
+    if match = scan(/\-\-\[\=*\[/)   #--[[ long (possibly multiline) comment ]]
+      @num_equals = match.count("=") # Number must match for comment end
+      @encoder.begin_group(:comment)
+      @encoder.text_token(match, :delimiter)
+      @state = :long_comment
+    elsif match = scan(/--.*?$/) # --Lua comment
+      @encoder.text_token(match, :comment)
+    elsif match = scan(/\[=*\[/)     # [[ long (possibly multiline) string ]]
+      @num_equals = match.count("=") # Number must match for comment end
+      @encoder.begin_group(:string)
+      @encoder.text_token(match, :delimiter)
+      @state = :long_string
+    elsif match = scan(/[\+\-\*\/%^\#=~<>\(\)\{\}\[\]:;,] | \.(?!\d)/x)
+      @encoder.text_token(match, :operator)
+    elsif match = scan(/[a-zA-Z_][a-zA-Z0-9_]*/) # Normal letters (or letters followed by digits)
+      kind = IDENT_KIND[match]
+
+      if kind == :keyword and match == "function"
+        @state = :function_expected
+      end
+
+      @encoder.text_token(match, kind)
+    elsif match = scan(/["']/)
+      @encoder.begin_group(:string)
+      @encoder.text_token(match, :delimiter)
+      @start_delim = match
+      @state = :string                            # hex number ←|→ decimal number
+    elsif match = scan(/0x(?:[0-9a-z])* \. [0-9a-z]+ (?:p-\d+)? | \d*\.\d+ (?:e[+\-]?\d+)?/ix) # hexadecimal constants have no E power, decimal ones no P power
+      @encoder.text_token(match, :float) # hex | decimal
+    elsif match = scan(/0x[0-9a-z]+ (?:p-\d+)? | \d+ (?:e[+\-]?\d+)?/ix) # hexadecimal constants have no E power, decimal ones no P power
+      @encoder.text_token(match, :integer)
+    elsif match = scan(/\s+/)
+      @encoder.text_token(match, :space)
+    else
+      @encoder.text_token(getch, :error)
+    end
+  end
+
+  def handle_state_function_expected
+    if match = scan(/[a-zA-Z_] (?:[a-zA-Z0-9_\.] (?!\.\d))* \./x) # function tbl.subtbl.foo()
+      @encoder.text_token(match, :ident)
+    elsif match = scan(/[a-zA-Z_][a-zA-Z0-9_]*/) # function foo()
+      @encoder.text_token(match, :function)
+      @state = :initial
+    elsif match = scan(/\s+/) # Between the function keyword and the ident may be any amount of whitespace
+      @encoder.text_token(match, :space)
+    else
+      @encoder.text_token(getch, :error)
+      @state = :initial
+    end
+  end
+
+  def handle_state_long_comment
+    if match = scan(/.*?(?=\]={#@num_equals}\])/m)
+      @encoder.text_token(match, :content)
+
+      delim = scan(/\]={#@num_equals}\]/)
+      @encoder.text_token(delim, :delimiter)
+    else # No terminator found till EOF
+      @encoder.text_token(rest, :error)
+      terminate
+    end
+    @encoder.end_group(:comment)
+    @state = :initial
+  end
+
+  def handle_state_long_string
+    if match = scan(/.*?(?=\]={#@num_equals}\])/m) # Long strings do not interpret any escape sequences
+      @encoder.text_token(match, :content)
+
+      delim = scan(/\]={#@num_equals}\]/)
+      @encoder.text_token(delim, :delimiter)
+    else # No terminator found till EOF
+      @encoder.text_token(rest, :error)
+      terminate
+    end
+    @encoder.end_group(:string)
+    @state = :initial
+  end
+
+  def handle_state_string
+    if match = scan(/[^\\#@start_delim\n]+/) # Everything except \ and the start delimiter character is string content (newlines are only allowed if preceeded by \ or \z)
+      @encoder.text_token(match, :content)
+    elsif match = scan(/\\(?:['"abfnrtv\\]|z\s*|x\h\h|\d{1,3}|\n)/m)
+      @encoder.text_token(match, :char)
+    elsif match = scan(Regexp.compile(@start_delim))
+      @encoder.text_token(match, :delimiter)
+      @encoder.end_group(:string)
+      @state = :initial
+    elsif match = scan(/\n/) # Lua forbids unescaped newlines in normal non-long strings
+      @encoder.text_token("\\n\n", :error) # Visually appealing error indicator--otherwise users may wonder whether the highlighter cannot highlight multine strings
+      @encoder.end_group(:string)
+      @state = :initial
+    else
+      @encoder.text_token(getch, :error)
+    end
+  end
+
+end