org.mozilla.javascript
Class Decompiler
java.lang.Object
org.mozilla.javascript.Decompiler
public class Decompiler
extends java.lang.Object
The following class save decompilation information about the source.
Source information is returned from the parser as a String
associated with function nodes and with the toplevel script. When
saved in the constant pool of a class, this string will be UTF-8
encoded, and token values will occupy a single byte.
Source is saved (mostly) as token numbers. The tokens saved pretty
much correspond to the token stream of a 'canonical' representation
of the input program, as directed by the parser. (There were a few
cases where tokens could have been left out where decompiler could
easily reconstruct them, but I left them in for clarity). (I also
looked adding source collection to TokenStream instead, where I
could have limited the changes to a few lines in getToken... but
this wouldn't have saved any space in the resulting source
representation, and would have meant that I'd have to duplicate
parser logic in the decompiler to disambiguate situations where
newlines are important.) The function decompile expands the
tokens back into their string representations, using simple
lookahead to correct spacing and indentation.
Assignments are saved as two-token pairs (Token.ASSIGN, op). Number tokens
are stored inline, as a NUMBER token, a character representing the type, and
either 1 or 4 characters representing the bit-encoding of the number. String
types NAME, STRING and OBJECT are currently stored as a token type,
followed by a character giving the length of the string (assumed to
be less than 2^16), followed by the characters of the string
inlined into the source string. Changing this to some reference to
to the string in the compiled class' constant pool would probably
save a lot of space... but would require some method of deriving
the final constant pool entry from information available at parse
time.
static int | CASE_GAP_PROP - Decompilation property to specify identation offset for case labels.
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static int | INDENT_GAP_PROP - Decompilation property to specify default identation offset.
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static int | INITIAL_INDENT_PROP - Decompilation property to specify initial ident value.
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static int | ONLY_BODY_FLAG - Flag to indicate that the decompilation should omit the
function header and trailing brace.
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static int | TO_SOURCE_FLAG - Flag to indicate that the decompilation generates toSource result.
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static String | decompile(String source, int flags, UintMap properties) - Decompile the source information associated with this js
function/script back into a string.
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CASE_GAP_PROP
public static final int CASE_GAP_PROP
Decompilation property to specify identation offset for case labels.
INDENT_GAP_PROP
public static final int INDENT_GAP_PROP
Decompilation property to specify default identation offset.
INITIAL_INDENT_PROP
public static final int INITIAL_INDENT_PROP
Decompilation property to specify initial ident value.
ONLY_BODY_FLAG
public static final int ONLY_BODY_FLAG
Flag to indicate that the decompilation should omit the
function header and trailing brace.
TO_SOURCE_FLAG
public static final int TO_SOURCE_FLAG
Flag to indicate that the decompilation generates toSource result.
decompile
public static String decompile(String source,
int flags,
UintMap properties)
Decompile the source information associated with this js
function/script back into a string. For the most part, this
just means translating tokens back to their string
representations; there's a little bit of lookahead logic to
decide the proper spacing/indentation. Most of the work in
mapping the original source to the prettyprinted decompiled
version is done by the parser.
source
- encoded source tree presentationflags
- flags to select output formatproperties
- indentation properties