Version 0.83

Added support for the CursorHoldI event so that the class/method/function is recognized also in Insert mode.

plugin/pythonhelper.vim

@@ -1,68 +1,452 @@
 " File: pythonhelper.vim
 " Author: Michal Vitecek <fuf-at-mageo-dot-cz>
-" Version: 0.7
+" Version: 0.83
-" Last Modified: Oct 2, 2002
+" Last Modified: Jan 4, 2010
 "
 " Overview
 " --------
 " Vim script to help moving around in larger Python source files. It displays
-" current class, method or function the cursor is placed in in the status
+" current class, method or function the cursor is placed in on the status
 " line for every python file. It's more clever than Yegappan Lakshmanan's
 " taglist.vim because it takes into account indetation and comments to
 " determine what tag the cursor is placed in.
 "
 " Requirements
 " ------------
-" This script needs VIM compiled with Python interpreter and relies on
+" This script needs only VIM compiled with Python interpreter. It doesn't rely
-" exuberant ctags utility to generate the tag listing. You can determine
+" on exuberant ctags utility. You can determine whether your VIM has Python
-" whether your VIM has Python support by issuing command :ver and looking for
+" support by issuing command :ver and looking for +python in the list of
-" +python in the list of features.
+" features.
-"
-" The exuberant ctags can be downloaded from http://ctags.sourceforge.net/ and
-" should be reasonably new version (tested with 5.3).
-"
-" Note: The script doesn't display current tag on the status line only in
-" NORMAL mode. This is because CursorHold event is fired up only in this mode.
-" However if you badly need to know what tag you are on even in INSERT or
-" VISUAL mode, contact me on the above specified email address and I'll send
-" you patch that enables it.
 "
 " Installation
 " ------------
 " 1. Make sure your Vim has python feature on (+python). If not, you will need
 "    to recompile it with --with-pythoninterp option to the configure script
 " 2. Copy script pythonhelper.vim to the $HOME/.vim/plugin directory
-" 3. Edit the script and modify the location of your exuberant tags utility
+" 3. Run Vim and open any python file.
-"    (variable CTAGS_PROGRAM).
-" 4. Run Vim and open any python file.
 " 
 python << EOS
 
 # import of required modules {{{
-import vim
+import re
-import os
-import popen2
-import time
 import sys
+import time
+import traceback
+import vim
 # }}}
 
 
-# CTAGS program and parameters {{{
-CTAGS_PROGRAM = "/usr/local/bin/ctags"
-CTAGS_PARAMETERS = "--language-force=python --format=2 --sort=0 --fields=+nK -L - -f - "
-# }}}
-
 # global dictionaries of tags and their line numbers, keys are buffer numbers {{{
-TAGS = {}
+TAGS            = {}
-TAGLINENUMBERS = {}
+TAGLINENUMBERS  = {}
-BUFFERTICKS = {}
+BUFFERTICKS     = {}
+# }}}
+
+
+# class PythonTag() {{{
+class PythonTag(object):
+    # DOC {{{
+    """A simple storage class representing a python tag.
+    """
+    # }}}
+
+
+    # STATIC VARIABLES {{{
+    
+    # possible tag types {{{
+    TT_CLASS                    = 0
+    TT_METHOD                   = 1
+    TT_FUNCTION                 = 2
+    # }}}
+
+    # tag type names {{{
+    TAG_TYPE_NAME               = {
+        TT_CLASS                : "class",
+        TT_METHOD               : "method",
+        TT_FUNCTION             : "function",
+    }
+    # }}}
+
+    # }}}
+
+
+    # METHODS {{{
+    
+    def __init__(self, type, name, fullName, lineNumber, indentLevel):
+        # DOC {{{
+        """Initializes instances of PythonTag().
+
+        Parameters
+            
+            type -- tag type
+
+            name -- short tag name
+
+            fullName -- full tag name (in dotted notation)
+
+            lineNumber -- line number on which the tag starts
+
+            indentLevel -- indentation level of the tag
+        """
+        # }}}
+
+        # CODE {{{
+        # remember the settings {{{
+        self.type               = type
+        self.name               = name
+        self.fullName           = fullName
+        self.lineNumber         = lineNumber
+        self.indentLevel        = indentLevel
+        # }}}
+        # }}}
+
+
+    def __str__(self):
+        # DOC {{{
+        """Returns a string representation of the tag.
+        """
+        # }}}
+
+        # CODE {{{
+        return "%s (%s) [%s, %u, %u]" % (self.name, PythonTag.TAG_TYPE_NAME[self.type],
+                                         self.fullName, self.lineNumber, self.indentLevel,)
+        # }}}
+
+
+    __repr__ = __str__
+
+
+    # }}}
+# }}}
+        
+
+# class SimplePythonTagsParser() {{{ 
+class SimplePythonTagsParser(object):
+    # DOC {{{
+    """Provides a simple python tag parser.
+    """
+    # }}}
+
+
+    # STATIC VARIABLES {{{
+
+    # how many chars a single tab represents (visually)
+    TABSIZE                     = 8
+    # regexp used to extract indentation and strip comments
+    COMMENTS_INDENT_RE          = re.compile('([ \t]*)([^\n#]*).*')
+    # regexp used to extract a class name
+    CLASS_RE                    = re.compile('class[ \t]+([^(:]+).*')
+    # regexp used to extract a method or function name
+    METHOD_RE                   = re.compile('def[ \t]+([^(]+).*')
+
+    # }}}
+
+
+    # METHODS {{{
+    
+    def __init__(self, source):
+        # DOC {{{
+        """Initializes instances of SimplePythonTagsParser().
+
+        Parameters
+
+            source -- source for which the tags will be generated. It must
+                provide callable method readline (i.e. as file objects do).
+        """
+        # }}}
+
+        # CODE {{{
+        # make sure source has readline() method {{{
+        if ((hasattr(source, 'readline') == 0) or
+            (callable(source.readline) == 0)):
+            raise AttributeError("Source must have callable readline method.")
+        # }}}
+                
+        # remember what the source is
+        self.source = source
+        # }}}
+
+    
+    def getTags(self):
+        # DOC {{{
+        """Determines all the tags for the buffer. Returns a tuple in format
+        (tagLineNumbers, tags,).
+        """
+        # }}}
+
+        # CODE {{{
+        # initialize the resulting list of the tag line numbers and the tag information {{{
+        tagLineNumbers  = []
+        tags            = {}
+        # }}}
+
+        # initalize local auxiliary variables {{{
+        tagsStack       = []
+        lineNumber      = 0
+        # }}}
+        
+        # go through all the lines in the source and localize all python tags in it {{{
+        while 1:
+            # get next line
+            line = self.source.readline()
+
+            # finish if this is the end of the source {{{
+            if (line == ''):
+                break
+            # }}}
+
+            # increase the line number
+            lineNumber += 1
+
+            # extract the line indentation characters and its content {{{
+            lineMatch           = self.COMMENTS_INDENT_RE.match(line)
+            lineContent         = lineMatch.group(2)
+            # }}}
+
+            # handle the class tag {{{
+            # match for the class tag
+            tagMatch = self.CLASS_RE.match(lineContent)
+
+            # if the class tag has been found, store some information on it {{{
+            if (tagMatch):
+                currentTag = self.getPythonTag(tagsStack, lineNumber, lineMatch.group(1),
+                                               tagMatch.group(1), self.tagClassTypeDecidingMethod)
+                tagLineNumbers.append(lineNumber)
+                tags[lineNumber] = currentTag
+            # }}}
+            # }}}
+            # handle the function/method/none tag {{{
+            else:
+                # match for the method/function tag
+                tagMatch = self.METHOD_RE.match(lineContent)
+
+                # if the method/function tag has been found, store some information on it {{{
+                if (tagMatch):
+                    currentTag = self.getPythonTag(tagsStack, lineNumber, lineMatch.group(1),
+                                                   tagMatch.group(1), self.tagFunctionTypeDecidingMethod)
+                    tagLineNumbers.append(lineNumber)
+                    tags[lineNumber] = currentTag
+                # }}}
+            # }}}
+        # }}}
+
+        # return the tags data for the source
+        return (tagLineNumbers, tags,)
+        # }}}
+
+
+    def getParentTag(self, tagsStack):
+        # DOC {{{
+        """Returns the parent/enclosing tag (instance of PythonTag()) from the
+        specified tag list. If no such parent tag exists, returns None.
+
+        Parameters
+
+            tagsStack -- list (stack) of currently open PythonTag() instances
+        """
+        # }}}
+
+        # CODE {{{
+        # determine the parent tag {{{
+        if (len(tagsStack)):
+            parentTag = tagsStack[-1]
+        else:
+            parentTag = None
+        # }}}
+         
+        # return the tag
+        return parentTag
+        # }}}
+
+
+    def computeIndentationLevel(indentChars):
+        # DOC {{{
+        """Computes the indentation level from the specified string.
+
+        Parameters
+
+            indentChars -- white space before any other character on line
+        """
+        # }}}
+
+        # CODE {{{
+        # initialize the indentation level
+        indentLevel = 0
+
+        # compute the indentation level (expand tabs) {{{
+        for char in indentChars:
+            if (char == '\t'):
+                indentLevel += SimplePythonTagsParser.TABSIZE
+            else:
+                indentLevel += 1
+        # }}}
+
+        # return the computed indentation level
+        return indentLevel
+        # }}}
+    computeIndentationLevel = staticmethod(computeIndentationLevel)
+
+
+    def getPythonTag(self, tagsStack, lineNumber, indentChars, tagName, tagTypeDecidingMethod):
+        # DOC {{{
+        """Returns instance of PythonTag() based on the specified data.
+
+        Parameters
+
+            tagsStack -- list (stack) of tags currently active. Note: Modified
+                in this method!
+
+            lineNumber -- current line number
+
+            indentChars -- characters making up the indentation level of the
+                current tag
+
+            tagName -- short name of the current tag
+
+            tagTypeDecidingMethod -- reference to method that is called to
+                determine the type of the current tag
+        """
+        # }}}
+
+        # CODE {{{
+        # compute the indentation level
+        indentLevel = self.computeIndentationLevel(indentChars)
+        # get the parent tag
+        parentTag = self.getParentTag(tagsStack)
+
+        # handle an enclosed tag {{{
+        while (parentTag):
+            # if the indent level of the parent tag is greater than of the current tag, use parent tag of the parent tag {{{
+            if (parentTag.indentLevel >= indentLevel):
+                del tagsStack[-1]
+            # }}}
+            # otherwise we have all information on the current tag and can return it {{{
+            else:
+                # create the tag
+                tag = PythonTag(tagTypeDecidingMethod(parentTag.type), tagName, "%s.%s" % (parentTag.fullName, tagName,), lineNumber, indentLevel)
+
+                # break the loop
+                break
+            # }}}
+
+            # use parent tag of the parent tag
+            parentTag = self.getParentTag(tagsStack)
+        # }}}
+        # handle a top-indent level tag {{{
+        else:
+            # create the tag
+            tag = PythonTag(tagTypeDecidingMethod(None), tagName, tagName, lineNumber, indentLevel)
+        # }}}
+
+        # add the tag to the list of tags
+        tagsStack.append(tag)
+
+        # return the tag
+        return tag
+        # }}}
+
+
+    def tagClassTypeDecidingMethod(self, parentTagType):
+        # DOC {{{
+        """Returns tag type of the current tag based on its previous tag (super
+        tag) for classes.
+
+        Parameters
+
+            parentTagType -- type of the enclosing/parent tag
+        """
+        # }}}
+
+        # CODE {{{
+        # is always class no matter what
+        return PythonTag.TT_CLASS
+        # }}}
+
+
+    def tagFunctionTypeDecidingMethod(self, parentTagType):
+        # DOC {{{
+        """Returns tag type of the current tag based on its previous tag (super
+        tag) for functions/methods.
+
+        Parameters
+        
+            parentTagType -- type of the enclosing/parent tag
+        """
+        # }}}
+
+        # CODE {{{
+        if (parentTagType == PythonTag.TT_CLASS):
+            return PythonTag.TT_METHOD
+        else:
+            return PythonTag.TT_FUNCTION
+        # }}}
+
+
+    # }}}
+# }}}
+
+
+# class VimReadlineBuffer() {{{
+class VimReadlineBuffer(object):
+    # DOC {{{
+    """A simple wrapper class around vim's buffer that provides readline
+    method.
+    """
+    # }}}
+
+
+    # METHODS {{{
+
+    def __init__(self, vimBuffer):
+        # DOC {{{
+        """Initializes instances of VimReadlineBuffer().
+
+        Parameters
+
+            vimBuffer -- VIM's buffer
+        """
+        # }}}
+
+        # CODE {{{
+        # remember the settings
+        self.vimBuffer          = vimBuffer
+
+        # initialize instance attributes {{{
+        self.currentLine        = -1
+        self.bufferLines        = len(vimBuffer)
+        # }}}
+        # }}}
+
+
+    def readline(self):
+        # DOC {{{
+        """Returns next line from the buffer. If all the buffer has been read,
+        returns empty string.
+        """
+        # }}}
+
+        # CODE {{{
+        # increase the current line counter
+        self.currentLine += 1
+
+        # notify end of file if we reached beyond the last line {{{
+        if (self.currentLine == self.bufferLines):
+            return ''
+        # }}}
+
+        # return the line with an added newline (vim stores the lines without it)
+        return "%s\n" % (self.vimBuffer[self.currentLine],)
+        # }}}
+
+    
+    # }}}
 # }}}
 
 
 def getNearestLineIndex(row, tagLineNumbers):
     # DOC {{{
-    """Returns index of line in tagLineNumbers list that is nearest to the
+    """Returns the index of line in 'tagLineNumbers' list that is nearest to the
-    current cursor row.
+    specified cursor row.
 
     Parameters
 
@@ -73,29 +457,34 @@ def getNearestLineIndex(row, tagLineNumbers):
     # }}}
 
     # CODE {{{
-    nearestLineNumber = -1
+    # initialize local auxiliary variables {{{
-    nearestLineIndex = -1
+    nearestLineNumber   = -1
-    i = 0
+    nearestLineIndex    = -1
-    for lineNumber in tagLineNumbers:
+    # }}}
+
+    # go through all tag line numbers and find the one nearest to the specified row {{{
+    for lineIndex, lineNumber in enumerate(tagLineNumbers):
 	# if the current line is nearer the current cursor position, take it {{{
 	if (nearestLineNumber < lineNumber <= row):
-	    nearestLineNumber = lineNumber
+	    nearestLineNumber   = lineNumber
-	    nearestLineIndex = i
+            nearestLineIndex    = lineIndex
 	# }}}
+
 	# if we've got past the current cursor position, let's end the search {{{
 	if (lineNumber >= row):
 	    break
 	# }}}
-	i += 1
+    # }}}
+
+    # return index of the line with the nearest tag
     return nearestLineIndex
     # }}}
 
 
 def getTags(bufferNumber, changedTick):
     # DOC {{{
-    """Reads the tags for the specified buffer number. It does so by executing
+    """Reads the tags for the specified buffer number. Returns a tuple
-    the CTAGS program and parsing its output. Returns tuple
+    (taglinenumber[buffer], tags[buffer],).
-    (taglinenumber[buffer], tags[buffer]).
 
     Parameters
 
@@ -107,92 +496,27 @@ def getTags(bufferNumber, changedTick):
     # }}}
 
     # CODE {{{
-    global	CTAGS_PROGRAM, CTAGS_PARAMETERS
+    # define global variables
-    global	TAGLINENUMBERS, TAGS, BUFFERTICKS
+    global TAGLINENUMBERS, TAGS, BUFFERTICKS
-
 
     # return immediately if there's no need to update the tags {{{
-    if ((BUFFERTICKS.has_key(bufferNumber)) and (BUFFERTICKS[bufferNumber] == changedTick)):
+    if (BUFFERTICKS.get(bufferNumber, None) == changedTick):
 	return (TAGLINENUMBERS[bufferNumber], TAGS[bufferNumber],)
     # }}}
 
-    # read the tags and fill the global variables {{{
+    # get the tags {{{
-    currentBuffer = vim.current.buffer
+    simpleTagsParser = SimplePythonTagsParser(VimReadlineBuffer(vim.current.buffer))
-    currentWindow = vim.current.window
+    tagLineNumbers, tags = simpleTagsParser.getTags()
-    row, col = currentWindow.cursor
-
-    # create a temporary file with the current content of the buffer {{{
-    fileName = "/tmp/.%s.%u.ph" % (os.path.basename(currentBuffer.name), os.getpid(),)
-    f = open(fileName, "w")
-
-    for line in currentBuffer:
-	f.write(line)
-	f.write('\n')
-    f.close()
-    # }}}
-
-    # run ctags on it {{{
-    try:
-	ctagsOutPut, ctagsInPut = popen2.popen4("%s %s" % (CTAGS_PROGRAM, CTAGS_PARAMETERS,))
-	ctagsInPut.write(fileName + "\n")
-	ctagsInPut.close()
-    except:
-	os.unlink(fileName)
-	return
-    # }}}
-
-    # parse the ctags' output {{{
-    tagLineNumbers = []
-    tags = {}
-    while 1:
-	line = ctagsOutPut.readline()
-        # if empty line has been read, it's the end of the file {{{
-	if (line == ''):
-	    break
-        # }}}
-        # if the line starts with !, then it's a comment line {{{
-	if (line[0] == '!'):
-	    continue
-        # }}}
-	
-        # split the line into parts and parse the data {{{
-        # the format is: [0]tagName [1]fileName [2]tagLine [3]tagType [4]tagLineNumber [[5]tagOwner]
-	tagData = line.split('\t')
-	name = tagData[0]
-        # get the tag's indentation {{{
-	start = 2
-	j = 2
-	while ((j < len(tagData[2])) and (tagData[2][j].isspace())):
-	    if (tagData[2][j] == '\t'):
-		start += 8
-	    else:
-		start += 1
-	    j += 1
-        # }}}
-	type = tagData[3]
-	line = int(tagData[4][5:])
-	if (len(tagData) == 6):
-	    owner = tagData[5].strip()
-	else:
-	    owner = None
-        # }}}
-	tagLineNumbers.append(line)
-	tags[line] = (name, type, owner, start)
-    ctagsOutPut.close()
-    # }}}
-
-    # clean up the now unnecessary stuff {{{
-    os.unlink(fileName)
     # }}}
 
     # update the global variables {{{
-    TAGS[bufferNumber] = tags
+    TAGS[bufferNumber]                  = tags
-    TAGLINENUMBERS[bufferNumber] = tagLineNumbers
+    TAGLINENUMBERS[bufferNumber]        = tagLineNumbers
-    BUFFERTICKS[bufferNumber] = changedTick
+    BUFFERTICKS[bufferNumber]           = changedTick
-    # }}}
     # }}}
 
-    return (TAGLINENUMBERS[bufferNumber], TAGS[bufferNumber],)
+    # return the tuple (tagLineNumbers, tags,)
+    return (tagLineNumbers, tags,)
     # }}}
 
 
@@ -210,11 +534,12 @@ def findTag(bufferNumber, changedTick):
     # }}}
 
     # CODE {{{
+    # try to find the best tag {{{
     try:
 	# get the tags data for the current buffer
 	tagLineNumbers, tags = getTags(bufferNumber, changedTick)
 
-	# link to vim internal data {{{
+	# link to vim's internal data {{{
 	currentBuffer = vim.current.buffer
 	currentWindow = vim.current.window
 	row, col = currentWindow.cursor
@@ -222,74 +547,97 @@ def findTag(bufferNumber, changedTick):
 
 	# get the index of the nearest line
 	nearestLineIndex = getNearestLineIndex(row, tagLineNumbers)
+
 	# if any line was found, try to find if the tag is appropriate {{{
 	# (ie. the cursor can be below the last tag but on a code that has nothing
 	# to do with the tag, because it's indented differently, in such case no
 	# appropriate tag has been found.)
-	if (nearestLineIndex > -1):
+        while (nearestLineIndex > -1):
-	    nearestLineNumber = tagLineNumbers[nearestLineIndex]
+            # get the line number of the nearest tag
-	    # walk through all the lines in range (nearestTagLine, cursorRow) {{{
+            nearestLineNumber = tagLineNumbers[nearestLineIndex]
-	    for i in xrange(nearestLineNumber + 1, row):
+
-		line = currentBuffer[i]
+            # walk through all the lines in range (nearestTagLine, cursorRow) {{{
-		# count the indentation of the line, if it's lower that the tag's, the found tag is wrong {{{
+            for lineNumber in xrange(nearestLineNumber + 1, row):
-		if (len(line)):
+                # get the current line
+                line = currentBuffer[lineNumber]
+
+                # count the indentation of the line, if it's lower than the tag's, the tag is invalid {{{
+                if (len(line)):
+                    # initialize local auxiliary variables {{{
+                    lineStart   = 0
+                    i           = 0
+                    # }}}
+
                     # compute the indentation of the line {{{
-		    lineStart = 0
+                    while ((i < len(line)) and (line[i].isspace())):
-		    j = 0
+                        # move the start of the line code {{{
-		    while ((j < len(line)) and (line[j].isspace())):
+                        if (line[i] == '\t'):
-			if (line[j] == '\t'):
+                            lineStart += SimplePythonTagsParser.TABSIZE
-			    lineStart += 8
+                        else:
-			else:
+                            lineStart += 1
-			    lineStart += 1
+                        # }}}
-			j += 1
+
-                    # if the line contains only spaces, it doesn't count {{{
+                        # go to the next character on the line
-                    if (j == len(line)):
+                        i += 1
+                    # }}}
+
+                    # if the line contains only spaces, skip it {{{
+                    if (i == len(line)):
                         continue
                     # }}}
-                    # if the next character is # (python comment), this line doesn't count {{{
+                    # if the next character is a '#' (python comment), skip the line {{{
-                    if (line[j] == '#'):
+                    if (line[i] == '#'):
                         continue
                     # }}}
+
+                    # if the line's indentation starts before or at the nearest tag's one, the tag is invalid {{{
+                    if (lineStart <= tags[nearestLineNumber].indentLevel):
+                        nearestLineIndex -= 1
+                        break
                     # }}}
-                    # if the line's indentation starts before the nearest tag's one, the tag is wrong {{{
+                # }}}
-		    if (lineStart < tags[nearestLineNumber][3]):
+            # }}}
-			nearestLineNumber = -1
+            # the tag is appropriate, so use it {{{
-			break
+            else:
-                    # }}}
+                break
-		# }}}
 	    # }}}
+        # }}}
+        # no appropriate tag has been found {{{
 	else:
 	    nearestLineNumber = -1
 	# }}}
 	 
-	# describe the cursor position (what tag it's in) {{{
+	# describe the cursor position (what tag the cursor is on) {{{
+        # reset the description
 	tagDescription = ""
+
+        # if an appropriate tag has been found, set the description accordingly {{{
 	if (nearestLineNumber > -1):
 	    tagInfo = tags[nearestLineNumber]
-	    # use the owner if any exists {{{
+	    tagDescription = "[in %s (%s)]" % (tagInfo.fullName, PythonTag.TAG_TYPE_NAME[tagInfo.type],)
-	    if (tagInfo[2] != None):
+	# }}}
-		fullTagName = "%s.%s()" % (tagInfo[2].split(':')[1], tagInfo[0],)
-	    # }}}
-	    # otherwise use just the tag name {{{
-	    else:
-		fullTagName = tagInfo[0]
-	    # }}}
-	    tagDescription = "[in %s (%s)]" % (fullTagName, tagInfo[1],)
 	# }}}
 
-	# update the variable for the status line so it will be updated next time
+	# update the variable for the status line so it get updated with the new description
 	vim.command("let w:PHStatusLine=\"%s\"" % (tagDescription,))
-    except:
+    # }}}
-        # spit out debugging information {{{
+
+    # handle possible exceptions {{{
+    except Exception:
+        # bury into the traceback {{{
 	ec, ei, tb = sys.exc_info()
 	while (tb != None):
 	    if (tb.tb_next == None):
 		break
 	    tb = tb.tb_next
+        # }}}
+
+        # spit out the error {{{
 	print "ERROR: %s %s %s:%u" % (ec.__name__, ei, tb.tb_frame.f_code.co_filename, tb.tb_lineno,)
 	time.sleep(0.5)
         # }}}
     # }}}
+    # }}}
 
 
 def deleteTags(bufferNumber):
@@ -303,8 +651,10 @@ def deleteTags(bufferNumber):
     # }}}
 
     # CODE {{{
+    # define global variables
     global TAGS, TAGLINENUMBERS, BUFFERTICKS
     
+    # try to delete the tags for the buffer {{{
     try:
         del TAGS[bufferNumber]
         del TAGLINENUMBERS[bufferNumber]
@@ -312,14 +662,16 @@ def deleteTags(bufferNumber):
     except:
         pass
     # }}}
+    # }}}
 
 
 EOS
 
+" VIM functions {{{
 
 function! PHCursorHold()
     " only python is supported {{{
-    if (exists('b:current_syntax') && (b:current_syntax != 'python'))
+    if (!exists('b:current_syntax') || (b:current_syntax != 'python'))
 	let w:PHStatusLine = ''
 	return
     endif
@@ -331,15 +683,62 @@ endfunction
 
 
 function! PHBufferDelete()
+    " set PHStatusLine for this window to empty string
+    let w:PHStatusLine = ""
+    
     " call python function deleteTags() with the cur
     execute 'python deleteTags(' . expand("<abuf>") . ')'
 endfunction
 
 
+function! TagInStatusLine()
+    " return value of w:PHStatusLine in case it's set
+    if (exists("w:PHStatusLine"))
+        return w:PHStatusLine
+    " otherwise just return empty string
+    else
+        return ""
+    endif
+endfunction
+
+
+function! PHPreviousClassMethod()
+    call search('^[ \t]*\(class\|def\)\>', 'bw')
+endfunction
+
+
+function! PHNextClassMethod()
+    call search('^[ \t]*\(class\|def\)\>', 'w')
+endfunction
+
+
+function! PHPreviousClass()
+    call search('^[ \t]*class\>', 'bw')
+endfunction
+
+
+function! PHNextClass()
+    call search('^[ \t]*class\>', 'w')
+endfunction
+
+
+function! PHPreviousMethod()
+    call search('^[ \t]*def\>', 'bw')
+endfunction
+
+
+function! PHNextMethod()
+    call search('^[ \t]*def\>', 'w')
+endfunction
+
+" }}}
+
+
+" event binding, vim customizing {{{
 
 " autocommands binding
-autocmd CursorHold * silent call PHCursorHold()
+autocmd CursorHold * call PHCursorHold()
-autocmd BufWinEnter * silent call PHCursorHold()
+autocmd CursorHoldI * call PHCursorHold()
 autocmd BufDelete * silent call PHBufferDelete()
 
 " time that determines after how long time of no activity the CursorHold event
@@ -352,7 +751,9 @@ highlight User1 gui=bold guifg=cyan guibg=black
 highlight User2 gui=bold guifg=black guibg=red
 " the status line will be displayed for every window
 set laststatus=2
-" set the status variable for the current window
-let w:PHStatusLine = ''
 " set the status line to display some useful information
-set stl=%-f%r\ %2*%m%*\ \ \ \ %1*%{w:PHStatusLine}%*%=[%l:%c]\ \ \ \ [buf\ %n]
+set stl=%-f%r\ %2*%m%*\ \ \ \ %1*%{TagInStatusLine()}%*%=[%l:%c]\ \ \ \ [buf\ %n]
+
+" }}}
+
+" vim:foldmethod=marker