Module: LineCache

Defined in:
lib/linecache.rb

Overview

module LineCache

Module caching lines of a file

Defined Under Namespace

Classes: LineCacheInfo

Constant Summary collapse

@@file_cache =

the cache

{}

Class Method Summary collapse

Class Method Details

.checkcache(filename = nil) ⇒ Object

Discard cache entries that are out of date. If filename is nil all entries in the file cache @@file_cache are checked.



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# File 'lib/linecache.rb', line 107

def checkcache(filename=nil)
  
  if !filename
    filenames = @@file_cache.keys()
  elsif @@file_cache.member?(filename)
    filenames = [filename]
  else
    return nil
  end

  for filename in filenames
    next unless @@file_cache.member?(filename)
    fullname = @@file_cache[filename].fullname
    if File.exist?(fullname)
      cache_info = @@file_cache[filename]
      stat = File.stat(fullname)
      if cache_info.size != stat.size or cache_info.mtime != stat.mtime
        @@file_cache.delete(filename)
      end
    else
      @@file_cache.delete(filename)
    end
  end
end

.clear_file_cache ⇒ Object

Clear the file cache entirely.



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# File 'lib/linecache.rb', line 87

def clear_file_cache()
  @@file_cache = {}
end

.getline(filename, lineno) ⇒ Object

Get line lineno from file named filename. Return nil if there was a problem. If a file named filename is not found, the function will look for it in the $: path array.

Examples:

lines = LineCache::getline('/tmp/myfile.rb)
# Same as above
$: << '/tmp'
lines = Dir.chdir('/tmp') do 
   lines = LineCache::getlines ('myfile.rb')
end



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# File 'lib/linecache.rb', line 73

def getline(filename, lineno)
  lines = getlines(filename)
  if (1..lines.size) === lineno
      return lines[lineno-1]
  else
      return nil
  end
end

.getlines(filename) ⇒ Object

Read lines of filename and cache the results. However filename was previously cached use the results from the cache.



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# File 'lib/linecache.rb', line 95

def getlines(filename)
  if @@file_cache.member?(filename)
      return @@file_cache[filename].lines
  else
      return update_cache(filename)
  end
end

.update_cache(filename) ⇒ Object

Update a cache entry and return its list of lines. if something’s wrong, discard the cache entry, and return an empty list.



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# File 'lib/linecache.rb', line 136

def update_cache(filename)

  return [] unless filename

  @@file_cache.delete(filename)
    
  fullname = File.expand_path(filename)

  if File.exist?(fullname)
    stat = File.stat(fullname)
  else
    basename = File.basename(filename)

    # try looking through the search path.
    stat = nil
    for dirname in $:
      fullname = File.join(dirname, basename)
      if File.exist?(fullname)
          stat = File.stat(fullname)
          break
      end
    end
    return [] unless stat
  end
  begin
    fp = File.open(fullname, 'r')
    lines = fp.readlines()
    fp.close()
  rescue 
    ##  print '*** cannot open', fullname, ':', msg
    return []
  end
  @@file_cache[filename] = LineCacheInfo.new(File.stat(fullname), lines, 
                                             fullname)
  return lines
end