Class | Ohcount::Detector
In: | lib/ohcount/detector.rb
Parent: | Object

The Detector determines which Monoglot or Polyglot should be used to parse a source file.

The Detector primarily uses filename extensions to identify languages.

The hash EXTENSION_MAP maps a filename extension to the name of a parser.

If a filename extension is not enough to determine the correct parser (for instance, the *.m extension can indicate either a Matlab or Objective-C file), then the EXTENSION_MAP hash will contain a symbol identifying a Ruby method which will be invoked. This Ruby method can examine the file contents and return the name of the correct parser.

Many source files do not have an extension. The method `disambiguate_nil` is called in these cases. The `file` command line tool is used to determine the type of file and select a parser.

The Detector is covered by DetectorTest.

### Methods

binary_buffer? binary_filename? detect disambiguate_aspx disambiguate_basic disambiguate_c_cpp disambiguate_cs disambiguate_fortran disambiguate_h_header disambiguate_in disambiguate_inc disambiguate_nil disambiguate_non_visual_basic disambiguate_using_emacs_mode extract_c_cpp_headers lines_matching matlab_or_objective_c php_instruction?

### Classes and Modules

Module Ohcount::Detector::ContainsM
Module Ohcount::Detector::ContainsVB

### Constants

EXTENSION_MAP | = | { '.ada' => "ada", '.adb' => "ada", '.ads' => "ada", '.as' => "actionscript", '.ascx' => :disambiguate_aspx, '.aspx' => :disambiguate_aspx, '.asm' => "assembler", '.awk' => "awk", '.b' => :disambiguate_non_visual_basic, '.bas' => :disambiguate_basic, '.bat' => "bat", '.bi' => :disambiguate_non_visual_basic, '.bmx' => "blitzmax", '.boo' => "boo", '.c' => "c", '.C' => "cpp", '.cc' => "cpp", '.ctp' => "php", '.cpp' => "cpp", '.css' => "css", '.c++' => "cpp", '.cxx' => "cpp", '.com' => "dcl", '.el' => "emacslisp", '.cs' => :disambiguate_cs, '.dylan' => "dylan", '.e' => "eiffel", '.ebuild' => "ebuild", '.eclass' => "ebuild", '.kdebuild-1' => "ebuild", '.erl' => "erlang", '.exheres-0' => "exheres", '.exlib' => "exheres", '.f' => :disambiguate_fortran, '.factor' => "factor", '.ftn' => :disambiguate_fortran, '.f77' => :disambiguate_fortran, '.f90' => :disambiguate_fortran, '.f95' => :disambiguate_fortran, '.f03' => :disambiguate_fortran, '.frag' => "glsl", '.frx' => "visualbasic", '.frm' => "visualbasic", '.glsl' => "glsl", '.groovy' => "groovy", '.h' => :disambiguate_h_header, '.haml' => 'haml', '.H' => "cpp", '.hpp' => "cpp", '.h++' => "cpp", '.hs' => "haskell", '.hx' => "haxe", '.hxx' => "cpp", '.hh' => "cpp", '.hrl' => "erlang", '.htm' => "html", '.html' => "html", '.in' => :disambiguate_in, '.inc' => :disambiguate_inc, '.j' => "objective_j", '.java' => "java", '.js' => "javascript", '.jsp' => "jsp", '.lua' => "lua", '.lsp' => "lisp", '.lisp' => "lisp", '.m' => :matlab_or_objective_c, '.mf' => 'metafont', '.mk' => 'make', '.ml' => "ocaml", '.mli' => "ocaml", '.mm' => "objective_c", '.mp' => 'metapost_with_tex', '.mxml' => 'mxml', '.nix' => 'nix', '.nse' => 'lua', '.pas' => "pascal", '.pp' => "pascal", '.php' => "php", '.php3' => "php", '.php4' => "php", '.php5' => "php", '.p6' => "perl", '.pl' => "perl", '.pm' => "perl", '.perl' => "perl", '.ph' => "perl", '.pod' => "perl", '.t' => "perl", '.pike' => "pike", '.pmc' => "c", '.pmod' => "pike", '.py' => "python", '.r' => "r", '.rhtml' => "rhtml", '.rb' => "ruby", '.rex' => "rexx", '.rexx' => "rexx", '.s' => "assembler", '.sc' => "scheme", '.scala' => "scala", '.scm' => "scheme", '.sps' => "scheme", '.sls' => "scheme", '.ss' => "scheme", '.sh' => "shell", '.sql' => "sql", '.st' => "smalltalk", '.str' => "stratego", '.tcl' => "tcl", '.tpl' => "html", '.vala' => "vala", '.vb' => "visualbasic", '.vba' => "visualbasic", '.vbs' => "visualbasic", '.vert' => "glsl", '.vhd' => "vhdl", '.vhdl' => "vhdl", '.vim' => "vim", '.xaml' => "xaml", '.xml' => "xml", '.xs' => "c", '.xsd' => "xmlschema", '.xsl' => "xslt", '.d' => 'dmd', '.di' => 'dmd', '.tex' => 'tex', '.ltx' => 'tex', '.latex' => 'tex' |  | If an extension maps to a string, that string must be the name of a glot. If an extension maps to a Ruby symbol, that symbol must be the name of a Ruby method which will return the name of a glot.
FILENAME_MAP | = | { 'Makefile' => 'make', 'GNUmakefile' => 'make', 'makefile' => 'make', 'Makefile.am' => 'automake', 'configure.in' => 'autoconf', 'configure.ac' => 'autoconf', 'configure' => 'autoconf' |  | Map full filenames to glots. The right hand side is a string or symbol as for EXTENSION_MAP.
CPP_HEADERS_MAP | = | %w[ algorithm array bitset cassert ccomplex cctype cerrno cfenv cfloat cinttypes ciso646 climits clocale cmath csetjmp csignal cstdarg cstdbool cstddef cstdint cstdio cstdlib cstring ctgmath ctime cwchar cwctype deque exception fstream functional iomanip ios iosfwd iostream istream iterator limits list locale map memory new numeric ostream queue random regex set sstream stack stdexcept streambuf string system_error tuple type_traits typeinfo unordered_map unordered_set utility valarray vector tr1/array tr1/ccomplex tr1/cctype tr1/cfenv tr1/cfloat tr1/cinttypes tr1/climits tr1/cmath tr1/complex tr1/cstdarg tr1/cstdbool tr1/cstdint tr1/cstdio tr1/cstdlib tr1/ctgmath tr1/ctime tr1/cwchar tr1/cwctype tr1/memory tr1/random tr1/regex tr1/tuple tr1/type_traits tr1/unordered_map tr1/unordered_set tr1/utility ].inject({}) { | h, k | h[k] = true ; |  | A map of headers that indicate C++, but that do not have C++-specific file extensions. This list is made from the Standard, plus Technical Report 1.
CPP_KEYWORDS_MAP | = | %w[ template typename class namespace ].inject({}) { | h, k | h[k] = true ; |  | A map of keywords that indicate C++.

### Public Class methods

binary_filename?(filename)

Based solely on the filename, makes a judgment whether a file is a binary format.

[Source]

    # File lib/ohcount/detector.rb, line 80
                    def self.binary_filename?(filename)
                            ignore = [
                                    ".aiff",
                                    ".au",
                                    ".avi",
                                    ".bmp",
                                    ".cache",
                                    ".dat",
                                    ".doc",
                                    ".gif",
                                    ".gz",
                                    ".icns",
                                    ".jar",
                                    ".jpeg",
                                    ".jpg",
                                    ".m4a",
                                    ".mov",
                                    ".mp3",
                                    ".mpg",
                                    ".ogg",
                                    ".pdf",
                                    ".png",
                                    ".pnt",
                                    ".ppt",
                                    ".qt",
                                    ".ra",
                                    ".svg",
                                    ".svgz",
                                    ".svn",
                                    ".swf",
                                    ".tar",
                                    ".tgz",
                                    ".tif",
                                    ".tiff",
                                    ".wav",
                                    ".xls",
                                    ".xlw",
                                    ".zip"
                                    ]
                            ignore.include?(File.extname(filename).downcase)
                    end

detect(source_file)

The primary entry point for the detector. Given a file context containing the file name, content, and an array of other filenames in the source tree, attempts to detect which language family (Monoglot or Polyglot) is in use for this file.

Returns nil if the language is not recognized or if the file does not contain any code.

Example:

      # List all C files in the 'src' directory
      Dir.entries("src").each do |file|
        context = Ohcount::SimpleFileContext.new(file)
        polyglot = Ohcount::Detector.detect(context)
        puts "#{file}" if polyglot == 'c'
      end

[Source]

    # File lib/ohcount/detector.rb, line 55
                    def self.detect(source_file)
                            return nil if binary_filename?(source_file.filename)
                            return nil if binary_buffer?(source_file.contents)

                            # start with filename and extension
                            polyglot = [
                                    lambda { | f | FILENAME_MAP[File.basename(source_file.filename)] },
                                    lambda { | f | EXTENSION_MAP[File.extname(source_file.filename)] },
                                    lambda { | f | EXTENSION_MAP[File.extname(source_file.filename).downcase] }
                            ].inject(nil) { | a, f | a and break a or f.call(source_file) }
                            case polyglot
                            when String
                                    # simplest case
                                    return polyglot if polyglot.is_a?(String)
                            when Symbol
                                    # extension is ambiguous - requires custom disambiguation
                                    self.send(polyglot, source_file)
                            when NilClass
                                    return disambiguate_nil(source_file)
                            else
                                    raise RuntimeError.new("Unknown file detection type")
                            end
                    end

### Protected Class methods

binary_buffer?(buffer)

Tests whether the provided buffer contains binary or text content. This is not fool-proof — we basically just check for zero values in the early bytes of the buffer. If we find a zero, we know it is not (ascii) text.

[Source]

    # File lib/ohcount/detector.rb, line 476
                    def self.binary_buffer?(buffer)
                            100.times do |i|
                                    return true if buffer[i] == 0
                            end
                            false
                    end

disambiguate_aspx(source_file)

A *.aspx file may be scripted with either C# or VB.NET.

[Source]

    # File lib/ohcount/detector.rb, line 533
                    def self.disambiguate_aspx(source_file)
                            if source_file.contents.match(/<%@\s*Page[^>]+Language="VB"[^>]+%>/i)
                                    'vb_aspx'
                            else
                                    'cs_aspx'
                            end
                    end

disambiguate_basic(source_file)

Attempts to tell apart VB, classic BASIC and structured BASIC. First, checks if it is classic BASIC based on syntax. If not checks for .vb, .bp, .frx and .frm files (associated with VB) in file context

If these files are absent, assumes structured BASIC

[Source]

    # File lib/ohcount/detector.rb, line 548
                    def self.disambiguate_basic(source_file)
                            classic_basic_line = /^\d+\s+\w+.*$/
                            vb_filename = /\.fr[mx]$|\.vb([aps]?)$/
                            buffer = source_file.contents
                            if lines_matching(buffer,classic_basic_line) > 0
                                    return 'classic_basic'
                            else
                                    unless defined?(source_file.filenames.contains_vb)
                                            source_file.filenames.extend(ContainsVB)
                                            source_file.filenames.contains_vb = source_file.filenames.select { |a| a =~ vb_filename }.any?
                                    end
                                    if source_file.filenames.contains_vb
                                            return 'visualbasic'
                                    else
                                            return 'structured_basic'
                                    end
                            end
                    end

disambiguate_c_cpp(buffer)

For *.h files that we know aren‘t Objective-C, differentiates C and C++.

This is done with a weighted heuristic that scans the *.h file contents for C++ keywords and C++ headers.

[Source]

    # File lib/ohcount/detector.rb, line 448
                    def self.disambiguate_c_cpp(buffer)
                            # Look for C++ headers
                            return 'cpp' if extract_c_cpp_headers(buffer).detect do | header |
                                    EXTENSION_MAP[File.extname(header)] == 'cpp' or CPP_HEADERS_MAP.include? header
                            end

                            # Look for C++ keywords. This could check for comments, but doesn't.
                            return 'cpp' if buffer.find do | line |
                                    line.split(/\W/).find do | word |
                                            CPP_KEYWORDS_MAP.include? word
                                    end
                            end

                            # Nothing to suggest C++
                            'c'
                    end

disambiguate_cs(source_file)

For files with extention *.cs, differentiates C# from Clearsilver.

[Source]

    # File lib/ohcount/detector.rb, line 509
                    def self.disambiguate_cs(source_file)
                            buffer = source_file.contents
                            return 'clearsilver_template' if lines_matching(source_file.contents, /\<\?cs/) > 0
                            return 'csharp'
                    end

disambiguate_fortran(source_file)

[Source]

    # File lib/ohcount/detector.rb, line 515
                    def self.disambiguate_fortran(source_file)
                            buffer = source_file.contents

                            definitely_not_f77 = /^ [^0-9 ]{5}/
                            return 'fortranfixed' if lines_matching(buffer, definitely_not_f77) > 0

                            free_form_continuation = /&\s*\n\s*&/m
                            return 'fortranfree' if buffer.match(free_form_continuation)

                            possibly_fixed = /^ [0-9 ]{5}/
                            contig_number = /^\s*\d+\s*$/
                            buffer.scan(possibly_fixed) {|leader|
                                    return 'fortranfixed' if !(leader =~ contig_number) }
                            # Might as well be free-form.
                            return 'fortranfree'
                    end

disambiguate_h_header(source_file)

For *.h files, differentiates C, C++ and Objective-C.

This is done with a weighted heuristic that scans the *.h file contents for Objective-C keywords, C++ keywords and C++ headers, and also checks for the presence of matching *.m files.

[Source]

    # File lib/ohcount/detector.rb, line 308
                    def self.disambiguate_h_header(source_file)
                            buffer = source_file.contents

                            # could it be realistically be objective_c ? are there any .m files at all?
                            # Speed hack - remember our findings in case we get the same filenames over and over
                            unless defined?(source_file.filenames.contains_m)
                                    source_file.filenames.extend(ContainsM)
                                    source_file.filenames.contains_m = source_file.filenames.select { |a| a =~ /\.m$/ }.any?
                                    source_file.filenames.contains_pike_or_pmod = source_file.filenames.select { |a| a =~ /\.p(ike|mod)$/ }.any?
                            end

                            if source_file.filenames.contains_m
                                    # if the dir contains a matching *.m file, likely objective_c
                                    if source_file.filename =~ /\.h$/
                                            m_counterpart = source_file.filename.gsub(/\.h$/, ".m")
                                            return 'objective_c' if source_file.filenames.include?(m_counterpart)
                                    end

                                    # ok - it just might be objective_c, let's check contents for objective_c signatures
                                    objective_c_signatures = /(^\s*@interface)|(^\s*@end)/
                                    objective_c = lines_matching(buffer, objective_c_signatures)
                                    return 'objective_c' if objective_c > 1
                            end

                            if source_file.filenames.contains_pike_or_pmod
                                    # The string "pike" and a selection of common Pike keywords.
                                    pike_signatures = /([Pp][Ii][Kk][Ee])|(string )|(mapping)|(multiset)|(import )|(inherit )|(predef)/
                                    pike = lines_matching(buffer, pike_signatures)
                                    return 'pike' if pike > 0
                            end

                            disambiguate_c_cpp(buffer)
                    end

disambiguate_in(source_file)

For *.in files, checks the prior extension. Typically used for template files (eg Makefile.in, auto.c.in, etc).

[Source]

    # File lib/ohcount/detector.rb, line 490
                    def self.disambiguate_in(source_file)
                            # only if the filename has an extension prior to the .in
                            return nil unless source_file.filename =~ /(.+\.(.*))\.in$/

                            undecorated_source = source_file.clone
                            undecorated_source.filename = $1

                            detect(undecorated_source)
                    end

disambiguate_inc(source_file)

For *.inc files, checks for a PHP class.

[Source]

    # File lib/ohcount/detector.rb, line 501
                    def self.disambiguate_inc(source_file)
                            buffer = source_file.contents
                            return nil if binary_buffer?(buffer)
                            return 'php' if php_instruction?(buffer)
                            nil
                    end

disambiguate_nil(source_file)

Attempts to determine the Polyglot for files that do not have a filename extension.

Relies on the bash `file` command line tool as its primary method.

There must be a file at `source_file.file_location` for `file` to operate on.

[Source]

    # File lib/ohcount/detector.rb, line 586
                    def self.disambiguate_nil(source_file)
                            script = disambiguate_using_emacs_mode(source_file)
                            return script if script

                            file_output = source_file.realize_file { |f| `file -b '#{ f }'` }
                            case file_output
                            when /([\w\/]+)(?: -[\w_]+)* script text/, /script text(?: executable)? for ([\w\/]+)/
                                    script = $1
                                    if script =~ /\/(\w*)$/
                                            script = $1
                                    end
                                    known_languages = EXTENSION_MAP.values
                                    return script.downcase if known_languages.include?(script.downcase)
                            when /([\w\-]*) shell script text/
                                    case $1
                                    when "Bourne-Again"
                                            return "shell"
                                    end
                            when /XML( 1\.0)? document text/, /^XML$/
                                    return 'xml'
                            end
                            # dang... no dice
                            nil
                    end

disambiguate_non_visual_basic(source_file)

[Source]

    # File lib/ohcount/detector.rb, line 567
                    def self.disambiguate_non_visual_basic(source_file)
                            classic_basic_line = /^\d+\s+\w+.*$/
                            buffer = source_file.contents

                            if lines_matching(buffer,classic_basic_line) > 0
                                    return 'classic_basic'
                            else
                                    return 'structured_basic'
                            end
                    end

disambiguate_using_emacs_mode(source_file)

[Source]

    # File lib/ohcount/detector.rb, line 611
                    def self.disambiguate_using_emacs_mode(source_file)
                            begin
                                    mode = nil

                                    # find the first line
                                    if source_file.contents =~ /^#!/
                                            # fetch 2 lines
                                            source_file.contents =~ /^(.*\n.*)\n/
                                    else
                                            # first line only
                                            source_file.contents =~ /^(.*)\n/
                                    end
                                    head = $1

                                    mode = case head
                                                             when /-\*-.*\bmode\s*:\s*([^\s;]+).*-\*-/i
                                                                     $1
                                                             when /-\*-\s*(\S+)\s*-\*-/
                                                                     $1
                                                             end
                                    if mode
                                            remap = {
                                                    'c++' => 'cpp',
                                                    'caml' => 'ocaml',
                                            }
                                            script = remap[mode] || mode

                                            known_languages = EXTENSION_MAP.values
                                            return script.downcase if known_languages.include?(script.downcase)
                                    end
                            rescue
                                    nil
                            end
                    end

extract_c_cpp_headers(buffer)

Return a list of files included in a C or C++ source file.

[Source]

    # File lib/ohcount/detector.rb, line 466
                    def self.extract_c_cpp_headers(buffer)
                            buffer.map do | line |
                                    m = line.match(/^#\s*include\s+[<"](.*)[>"]/) and m[1]
                            end.find_all { | a | a }
                    end

lines_matching(buffer, re)

Returns a count of lines in the buffer matching the given regular expression.

[Source]

    # File lib/ohcount/detector.rb, line 272
                    def self.lines_matching(buffer, re)
                            buffer.inject(0) { |total, line| line =~ re ? total+1 : total }
                    end

matlab_or_objective_c(source_file)

For *.m files, differentiates Matlab from Objective-C.

This is done with a weighted heuristic that scans the *.m file contents for keywords, and also checks for the presence of matching *.h files.

[Source]

    # File lib/ohcount/detector.rb, line 281
                    def self.matlab_or_objective_c(source_file)
                            buffer = source_file.contents

                            # if there are .h files in same directory, this probably isn't matlab
                            h_headers = 0.0
                            h_headers = -0.5 if source_file.filenames.select { |a| a =~ /\.h$/ }.any?

                            # if the contents contain 'function (' on a single line - very likely to be matlab
                            # if the contents contain lines starting with '%', its probably matlab comments
                            matlab_signatures = /(^\s*function\s*)|(^\s*%)/
                            matlab_sig_score = 0.1 * lines_matching(buffer, matlab_signatures)

                            # if the contents contains '//' or '/*', likely objective_c
                            objective_c_signatures = /(^\s*\/\/\s*)|(^\s*\/\*)|(^[+-])/
                            obj_c_sig_score = -0.1 * lines_matching(buffer, objective_c_signatures)

                            matlab = h_headers + matlab_sig_score + obj_c_sig_score

                            matlab > 0 ? 'matlab' : 'objective_c'
                    end

php_instruction?(buffer)

True if the provided buffer includes a ’?php’ directive

[Source]

    # File lib/ohcount/detector.rb, line 484
                    def self.php_instruction?(buffer)
                            buffer =~ /\?php/
                    end

[Validate]