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copied!<p>I don't see where's the problem.</p> <p>What about the following code ?</p> <pre><code>import re pat = '(=\s*).+?(?=\s*(#|$))' rgx = re.compile(pat,re.MULTILINE) su = '''log_File = a.log ### the path for log log_File = a.log log_File = a.log''' print su print print rgx.sub('\\1Hello',su) </code></pre> <p>.</p> <h3>EDIT</h3> <p>.</p> <p>I have seen where's the problem !</p> <p>As I wrote it, I don't think that the problem can be simply solved by only regex or a relatively simple function, because changing the right-part of an assignement (attribute called <strong>value</strong> in the AST node of an assignement) without touching the possible comment requires a syntactic analyze to determine what is the left-part of an assignement (attribute called <strong>targets</strong> in an AST node of an assignement), what is the right-part and what is the possible comment in a line. And even if a line isn't an assignement instruction, a syntactic analyze is required to determine it.</p> <p>For such a task there's only the module <code>ast</code>, which <em>helps Python applications to process trees of the Python abstract syntax grammar</em>, that can provide the tools to achieve the goal, in my opinion.</p> <p>Here's the code I succeeded to write on this idea:</p> <pre><code>import re,ast from sys import exit su = '''# it's nothing import re def funcg(a,b):\r print a*b + 900 x = "abc#ghi"\t\t# comment k = 103 dico["abc#12"] = [(x,x//3==0) for x in xrange(25) if x !=12] dico["ABC#12"] = 45 # comment a = 'lulu#88' dico["mu=$*"] = 'mouth#30' #ohoh log_File = a.log y = b.log ### x = a.log ''' print su def subst_assign_val_in_line(line,b0,repl): assert(isinstance(b0,ast.AST)) coloffset = b0.value.col_offset VA = line[coloffset:] try: yy = compile(VA+'\n',"-expr-",'eval') except: # because of a bug of ast in computing VA coloffset = coloffset - 1 VA = line[coloffset:] yy = compile(VA+'\n',"-expr-",'eval') gen = ((i,c) for i,c in enumerate(VA) if c=='#') for i,c in gen: VAshort = VA[0:i] # <== cuts in front of a # character try: yyi = compile(VAshort+'\n',"-exprshort-",'eval') except: pass else: if yy==yyi: return (line[0:coloffset] + repl + ' ' + line[coloffset+i:]) break else: print 'VA = line[%d:]' % coloffset print 'VA : %r' % VA print ' yy != yyi on:' print 'VAshort : %r' % VAshort raw_input(' **** UNIMAGINABLE CASE ***') else: return line[0:coloffset] + repl def subst_assigns_vals_in_text(text,repl, rgx = re.compile('\A([ \t]*)(.*)')): def yi(text): for line in text.splitlines(): head,line = rgx.search(line).groups() try: body = ast.parse(line,'line','exec').body except: yield head + line else: if isinstance(body,list): if len(body)==0: yield head + line elif len(body)==1: if type(body[0])==ast.Assign: yield head + subst_assign_val_in_line(line, body[0], repl) else: yield head + line else: print "list ast.parse(line,'line','exec').body has more than 1 element" print body exit() else: print "ast.parse(line,'line','exec').body is not a list" print body exit() return '\n'.join(yi(text)) print subst_assigns_vals_in_text(su,repl='Hello') </code></pre> <p>In fact, I wrote it accompanied with instructions <code>print</code> and the help of a personnal programm to display an AST tree in a readable manner (for me).<br> Here after is the code with instructions <code>print</code> only, to follow the process:</p> <pre><code>import re,ast from sys import exit su = '''# it's nothing import re def funcg(a,b):\r print a*b + 900 x = "abc#ghi"\t\t# comment k = 103 dico["abc#12"] = [(x,x//3==0) for x in xrange(25) if x !=12] dico["ABC#12"] = 45 # comment a = 'lulu#88' dico["mu=$*"] = 'mouth#30' #ohoh log_File = a.log y = b.log ### x = a.log ''' print su print '#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-#-' def subst_assign_val_in_line(line,b0,repl): assert(isinstance(b0,ast.AST)) print '\n%%%%%%%%%%%%%%%%\nline : %r' % line print '\nb0 == body[0]: ',b0 print '\nb0.value: ',b0.value print '\nb0.value.col_offset==',b0.value.col_offset coloffset = b0.value.col_offset VA = line[coloffset:] try: yy = compile(VA+'\n',"-expr-",'eval') except: # because of a bug of ast in computing VA coloffset = coloffset - 1 VA = line[coloffset:] yy = compile(VA+'\n',"-expr-",'eval') print 'VA = line[%d:]' % coloffset print 'VA : %r' % VA print ("yy = compile(VA+'\\n',\"-expr-\",'eval')\n" 'yy =='),yy gen = ((i,c) for i,c in enumerate(VA) if c=='#') deb = ("mwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmw\n" " mwmwmwm '#' in VA mwmwmwm\n") for i,c in gen: print '%si == %d VA[%d] == %r' % (deb,i,i,c) deb = '' VAshort = VA[0:i] # <== cuts in front of a # character print ' VAshort = VA[0:%d] == %r' % (i,VAshort) try: yyi = compile(VAshort+'\n',"-exprshort-",'eval') except: print " compile(%r+'\\n',\"-exprshort-\",'eval') gives error" % VAshort else: print (" yyi = compile(VAshort+'\\n',\"-exprshort-\",'eval')\n" ' yyi =='),yy if yy==yyi: print ' yy==yyi Real value of assignement found' print "mwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmw" return (line[0:coloffset] + repl + ' ' + line[coloffset+i:]) break else: print 'VA = line[%d:]' % coloffset print 'VA : %r' % VA print ' yy != yyi on:' print 'VAshort : %r' % VAshort raw_input(' **** UNIMAGINABLE CASE ***') else: return line[0:coloffset] + repl def subst_assigns_vals_in_text(text,repl, rgx = re.compile('\A([ \t]*)(.*)')): def yi(text): for line in text.splitlines(): raw_input('\n\npause') origline = line head,line = rgx.search(line).groups() print ('#########################################\n' '#########################################\n' 'line : %r\n' 'cut line : %r' % (origline,line)) try: body = ast.parse(line,'line','exec').body except: yield head + line else: if isinstance(body,list): if len(body)==0: yield head + line elif len(body)==1: if type(body[0])==ast.Assign: yield head + subst_assign_val_in_line(line, body[0], repl) else: yield head + line else: print "list ast.parse(line,'line','exec').body has more than 1 element" print body exit() else: print "ast.parse(line,'line','exec').body is not a list" print body exit() #in place of return '\n'.join(yi(text)) , to print the output def returning(text): for output in yi(text): print 'output : %r' % output yield output return '\n'.join(returning(text)) print '\n\n\n%s' % subst_assigns_vals_in_text(su,repl='Hello') </code></pre> <p>I don't give explanations because it would be too long to explain the structure of the AST tree of a code created by <code>ast.parse()</code>. I xwill give some lights on my code if asked</p> <p><strong>NB</strong> there's a bug in the functionning of <code>ast.parse()</code> when it gives the line and column at which begins certain nodes, so I was obliged to correct that byadditional lines of instructions.<br> For example, it gives a false result on a list comprehension. </p>

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