| #!/usr/bin/python2.4 |
| |
| # Copyright 2012 the V8 project authors. All rights reserved. |
| # Redistribution and use in source and binary forms, with or without |
| # modification, are permitted provided that the following conditions are |
| # met: |
| # |
| # * Redistributions of source code must retain the above copyright |
| # notice, this list of conditions and the following disclaimer. |
| # * Redistributions in binary form must reproduce the above |
| # copyright notice, this list of conditions and the following |
| # disclaimer in the documentation and/or other materials provided |
| # with the distribution. |
| # * Neither the name of Google Inc. nor the names of its |
| # contributors may be used to endorse or promote products derived |
| # from this software without specific prior written permission. |
| # |
| # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| """A JavaScript minifier. |
| |
| It is far from being a complete JS parser, so there are many valid |
| JavaScript programs that will be ruined by it. Another strangeness is that |
| it accepts $ and % as parts of identifiers. It doesn't merge lines or strip |
| out blank lines in order to ease debugging. Variables at the top scope are |
| properties of the global object so we can't rename them. It is assumed that |
| you introduce variables with var as if JavaScript followed C++ scope rules |
| around curly braces, so the declaration must be above the first use. |
| |
| Use as: |
| import jsmin |
| minifier = JavaScriptMinifier() |
| program1 = minifier.JSMinify(program1) |
| program2 = minifier.JSMinify(program2) |
| """ |
| |
| import re |
| |
| |
| class JavaScriptMinifier(object): |
| """An object that you can feed code snippets to to get them minified.""" |
| |
| def __init__(self): |
| # We prepopulate the list of identifiers that shouldn't be used. These |
| # short language keywords could otherwise be used by the script as variable |
| # names. |
| self.seen_identifiers = {"do": True, "in": True} |
| self.identifier_counter = 0 |
| self.in_comment = False |
| self.map = {} |
| self.nesting = 0 |
| |
| def LookAtIdentifier(self, m): |
| """Records identifiers or keywords that we see in use. |
| |
| (So we can avoid renaming variables to these strings.) |
| Args: |
| m: The match object returned by re.search. |
| |
| Returns: |
| Nothing. |
| """ |
| identifier = m.group(1) |
| self.seen_identifiers[identifier] = True |
| |
| def Push(self): |
| """Called when we encounter a '{'.""" |
| self.nesting += 1 |
| |
| def Pop(self): |
| """Called when we encounter a '}'.""" |
| self.nesting -= 1 |
| # We treat each top-level opening brace as a single scope that can span |
| # several sets of nested braces. |
| if self.nesting == 0: |
| self.map = {} |
| self.identifier_counter = 0 |
| |
| def Declaration(self, m): |
| """Rewrites bits of the program selected by a regexp. |
| |
| These can be curly braces, literal strings, function declarations and var |
| declarations. (These last two must be on one line including the opening |
| curly brace of the function for their variables to be renamed). |
| |
| Args: |
| m: The match object returned by re.search. |
| |
| Returns: |
| The string that should replace the match in the rewritten program. |
| """ |
| matched_text = m.group(0) |
| |
| if matched_text.startswith("`") and matched_text.endswith("`"): |
| return re.sub(r"\$\{([\w$%]+)\}", |
| lambda m: '${' + self.FindNewName(m.group(1)) + '}', |
| matched_text) |
| |
| if matched_text == "{": |
| self.Push() |
| return matched_text |
| if matched_text == "}": |
| self.Pop() |
| return matched_text |
| if re.match("[\"'/]", matched_text): |
| return matched_text |
| m = re.match(r"var ", matched_text) |
| if m: |
| var_names = matched_text[m.end():] |
| var_names = re.split(r",", var_names) |
| return "var " + ",".join(map(self.FindNewName, var_names)) |
| m = re.match(r"(function\b[^(]*)\((.*)\)\{$", matched_text) |
| if m: |
| up_to_args = m.group(1) |
| args = m.group(2) |
| args = re.split(r",", args) |
| self.Push() |
| return up_to_args + "(" + ",".join(map(self.FindNewName, args)) + "){" |
| |
| if matched_text in self.map: |
| return self.map[matched_text] |
| |
| return matched_text |
| |
| def CharFromNumber(self, number): |
| """A single-digit base-52 encoding using a-zA-Z.""" |
| if number < 26: |
| return chr(number + 97) |
| number -= 26 |
| return chr(number + 65) |
| |
| def FindNewName(self, var_name): |
| """Finds a new 1-character or 2-character name for a variable. |
| |
| Enters it into the mapping table for this scope. |
| |
| Args: |
| var_name: The name of the variable before renaming. |
| |
| Returns: |
| The new name of the variable. |
| """ |
| new_identifier = "" |
| # Variable names that end in _ are member variables of the global object, |
| # so they can be visible from code in a different scope. We leave them |
| # alone. |
| if var_name in self.map: |
| return self.map[var_name] |
| if self.nesting == 0: |
| return var_name |
| # Do not rename arguments object. |
| if var_name == 'arguments': |
| return 'arguments' |
| while True: |
| identifier_first_char = self.identifier_counter % 52 |
| identifier_second_char = self.identifier_counter // 52 |
| new_identifier = self.CharFromNumber(identifier_first_char) |
| if identifier_second_char != 0: |
| new_identifier = ( |
| self.CharFromNumber(identifier_second_char - 1) + new_identifier) |
| self.identifier_counter += 1 |
| if not new_identifier in self.seen_identifiers: |
| break |
| |
| self.map[var_name] = new_identifier |
| return new_identifier |
| |
| def RemoveSpaces(self, m): |
| """Returns literal strings unchanged, replaces other inputs with group 2. |
| |
| Other inputs are replaced with the contents of capture 1. This is either |
| a single space or an empty string. |
| |
| Args: |
| m: The match object returned by re.search. |
| |
| Returns: |
| The string that should be inserted instead of the matched text. |
| """ |
| entire_match = m.group(0) |
| replacement = m.group(1) |
| if re.match(r"'.*'$", entire_match): |
| return entire_match |
| if re.match(r'".*"$', entire_match): |
| return entire_match |
| if re.match(r"`.*`$", entire_match): |
| return entire_match |
| if re.match(r"/.+/$", entire_match): |
| return entire_match |
| return replacement |
| |
| def JSMinify(self, text): |
| """The main entry point. Takes a text and returns a compressed version. |
| |
| The compressed version hopefully does the same thing. Line breaks are |
| preserved. |
| |
| Args: |
| text: The text of the code snippet as a multiline string. |
| |
| Returns: |
| The compressed text of the code snippet as a multiline string. |
| """ |
| new_lines = [] |
| for line in re.split(r"\n", text): |
| line = line.replace("\t", " ") |
| if self.in_comment: |
| m = re.search(r"\*/", line) |
| if m: |
| line = line[m.end():] |
| self.in_comment = False |
| else: |
| new_lines.append("") |
| continue |
| |
| if not self.in_comment: |
| line = re.sub(r"/\*.*?\*/", " ", line) |
| line = re.sub(r"//.*", "", line) |
| m = re.search(r"/\*", line) |
| if m: |
| line = line[:m.start()] |
| self.in_comment = True |
| |
| # Strip leading and trailing spaces. |
| line = re.sub(r"^ +", "", line) |
| line = re.sub(r" +$", "", line) |
| # A regexp that matches a literal string surrounded by "double quotes". |
| # This regexp can handle embedded backslash-escaped characters including |
| # embedded backslash-escaped double quotes. |
| double_quoted_string = r'"(?:[^"\\]|\\.)*"' |
| # A regexp that matches a literal string surrounded by 'single quotes'. |
| single_quoted_string = r"'(?:[^'\\]|\\.)*'" |
| # A regexp that matches a template string |
| template_string = r"`(?:[^`\\]|\\.)*`" |
| # A regexp that matches a regexp literal surrounded by /slashes/. |
| # Don't allow a regexp to have a ) before the first ( since that's a |
| # syntax error and it's probably just two unrelated slashes. |
| # Also don't allow it to come after anything that can only be the |
| # end of a primary expression. |
| slash_quoted_regexp = r"(?<![\w$'\")\]])/(?:(?=\()|(?:[^()/\\]|\\.)+)(?:\([^/\\]|\\.)*/" |
| # Replace multiple spaces with a single space. |
| line = re.sub("|".join([double_quoted_string, |
| single_quoted_string, |
| template_string, |
| slash_quoted_regexp, |
| "( )+"]), |
| self.RemoveSpaces, |
| line) |
| # Strip single spaces unless they have an identifier character both before |
| # and after the space. % and $ are counted as identifier characters. |
| line = re.sub("|".join([double_quoted_string, |
| single_quoted_string, |
| template_string, |
| slash_quoted_regexp, |
| r"(?<![a-zA-Z_0-9$%]) | (?![a-zA-Z_0-9$%])()"]), |
| self.RemoveSpaces, |
| line) |
| # Collect keywords and identifiers that are already in use. |
| if self.nesting == 0: |
| re.sub(r"([a-zA-Z0-9_$%]+)", self.LookAtIdentifier, line) |
| function_declaration_regexp = ( |
| r"\bfunction" # Function definition keyword... |
| r"( [\w$%]+)?" # ...optional function name... |
| r"\([\w$%,]+\)\{") # ...argument declarations. |
| # Unfortunately the keyword-value syntax { key:value } makes the key look |
| # like a variable where in fact it is a literal string. We use the |
| # presence or absence of a question mark to try to distinguish between |
| # this case and the ternary operator: "condition ? iftrue : iffalse". |
| if re.search(r"\?", line): |
| block_trailing_colon = r"" |
| else: |
| block_trailing_colon = r"(?![:\w$%])" |
| # Variable use. Cannot follow a period precede a colon. |
| variable_use_regexp = r"(?<![.\w$%])[\w$%]+" + block_trailing_colon |
| line = re.sub("|".join([double_quoted_string, |
| single_quoted_string, |
| template_string, |
| slash_quoted_regexp, |
| r"\{", # Curly braces. |
| r"\}", |
| r"\bvar [\w$%,]+", # var declarations. |
| function_declaration_regexp, |
| variable_use_regexp]), |
| self.Declaration, |
| line) |
| new_lines.append(line) |
| |
| return "\n".join(new_lines) + "\n" |
