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Edit File: CodeContext.py

"""CodeContext - Extension to display the block context above the edit window Once code has scrolled off the top of a window, it can be difficult to determine which block you are in. This extension implements a pane at the top of each IDLE edit window which provides block structure hints. These hints are the lines which contain the block opening keywords, e.g. 'if', for the enclosing block. The number of hint lines is determined by the numlines variable in the CodeContext section of config-extensions.def. Lines which do not open blocks are not shown in the context hints pane. """ import Tkinter from Tkconstants import TOP, LEFT, X, W, SUNKEN import re from sys import maxint as INFINITY from idlelib.configHandler import idleConf BLOCKOPENERS = set(["class", "def", "elif", "else", "except", "finally", "for", "if", "try", "while", "with"]) UPDATEINTERVAL = 100 # millisec FONTUPDATEINTERVAL = 1000 # millisec getspacesfirstword =\ lambda s, c=re.compile(r"^(\s*)(\w*)"): c.match(s).groups() class CodeContext: menudefs = [('options', [('!Code Conte_xt', '<<toggle-code-context>>')])] context_depth = idleConf.GetOption("extensions", "CodeContext", "numlines", type="int", default=3) bgcolor = idleConf.GetOption("extensions", "CodeContext", "bgcolor", type="str", default="LightGray") fgcolor = idleConf.GetOption("extensions", "CodeContext", "fgcolor", type="str", default="Black") def __init__(self, editwin): self.editwin = editwin self.text = editwin.text self.textfont = self.text["font"] self.label = None # self.info is a list of (line number, indent level, line text, block # keyword) tuples providing the block structure associated with # self.topvisible (the linenumber of the line displayed at the top of # the edit window). self.info[0] is initialized as a 'dummy' line which # starts the toplevel 'block' of the module. self.info = [(0, -1, "", False)] self.topvisible = 1 visible = idleConf.GetOption("extensions", "CodeContext", "visible", type="bool", default=False) if visible: self.toggle_code_context_event() self.editwin.setvar('<<toggle-code-context>>', True) # Start two update cycles, one for context lines, one for font changes. self.text.after(UPDATEINTERVAL, self.timer_event) self.text.after(FONTUPDATEINTERVAL, self.font_timer_event) def toggle_code_context_event(self, event=None): if not self.label: # Calculate the border width and horizontal padding required to # align the context with the text in the main Text widget. # # All values are passed through int(str(<value>)), since some # values may be pixel objects, which can't simply be added to ints. widgets = self.editwin.text, self.editwin.text_frame # Calculate the required vertical padding padx = 0 for widget in widgets: padx += int(str( widget.pack_info()['padx'] )) padx += int(str( widget.cget('padx') )) # Calculate the required border width border = 0 for widget in widgets: border += int(str( widget.cget('border') )) self.label = Tkinter.Label(self.editwin.top, text="\n" * (self.context_depth - 1), anchor=W, justify=LEFT, font=self.textfont, bg=self.bgcolor, fg=self.fgcolor, width=1, #don't request more than we get padx=padx, border=border, relief=SUNKEN) # Pack the label widget before and above the text_frame widget, # thus ensuring that it will appear directly above text_frame self.label.pack(side=TOP, fill=X, expand=False, before=self.editwin.text_frame) else: self.label.destroy() self.label = None idleConf.SetOption("extensions", "CodeContext", "visible", str(self.label is not None)) idleConf.SaveUserCfgFiles() def get_line_info(self, linenum): """Get the line indent value, text, and any block start keyword If the line does not start a block, the keyword value is False. The indentation of empty lines (or comment lines) is INFINITY. """ text = self.text.get("%d.0" % linenum, "%d.end" % linenum) spaces, firstword = getspacesfirstword(text) opener = firstword in BLOCKOPENERS and firstword if len(text) == len(spaces) or text[len(spaces)] == '#': indent = INFINITY else: indent = len(spaces) return indent, text, opener def get_context(self, new_topvisible, stopline=1, stopindent=0): """Get context lines, starting at new_topvisible and working backwards. Stop when stopline or stopindent is reached. Return a tuple of context data and the indent level at the top of the region inspected. """ assert stopline > 0 lines = [] # The indentation level we are currently in: lastindent = INFINITY # For a line to be interesting, it must begin with a block opening # keyword, and have less indentation than lastindent. for linenum in xrange(new_topvisible, stopline-1, -1): indent, text, opener = self.get_line_info(linenum) if indent < lastindent: lastindent = indent if opener in ("else", "elif"): # We also show the if statement lastindent += 1 if opener and linenum < new_topvisible and indent >= stopindent: lines.append((linenum, indent, text, opener)) if lastindent <= stopindent: break lines.reverse() return lines, lastindent def update_code_context(self): """Update context information and lines visible in the context pane. """ new_topvisible = int(self.text.index("@0,0").split('.')[0]) if self.topvisible == new_topvisible: # haven't scrolled return if self.topvisible < new_topvisible: # scroll down lines, lastindent = self.get_context(new_topvisible, self.topvisible) # retain only context info applicable to the region # between topvisible and new_topvisible: while self.info[-1][1] >= lastindent: del self.info[-1] elif self.topvisible > new_topvisible: # scroll up stopindent = self.info[-1][1] + 1 # retain only context info associated # with lines above new_topvisible: while self.info[-1][0] >= new_topvisible: stopindent = self.info[-1][1] del self.info[-1] lines, lastindent = self.get_context(new_topvisible, self.info[-1][0]+1, stopindent) self.info.extend(lines) self.topvisible = new_topvisible # empty lines in context pane: context_strings = [""] * max(0, self.context_depth - len(self.info)) # followed by the context hint lines: context_strings += [x[2] for x in self.info[-self.context_depth:]] self.label["text"] = '\n'.join(context_strings) def timer_event(self): if self.label: self.update_code_context() self.text.after(UPDATEINTERVAL, self.timer_event) def font_timer_event(self): newtextfont = self.text["font"] if self.label and newtextfont != self.textfont: self.textfont = newtextfont self.label["font"] = self.textfont self.text.after(FONTUPDATEINTERVAL, self.font_timer_event)