Class TokenStreamRewriter
You can insert stuff, replace, and delete chunks. Note that the operations
are done lazily--only if you convert the buffer to a String
with
TokenStream.getText()
. This is very efficient because you are not
moving data around all the time. As the buffer of tokens is converted to
strings, the getText()
method(s) scan the input token stream and
check to see if there is an operation at the current index. If so, the
operation is done and then normal String
rendering continues on the
buffer. This is like having multiple Turing machine instruction streams
(programs) operating on a single input tape. :)
This rewriter makes no modifications to the token stream. It does not ask the
stream to fill itself up nor does it advance the input cursor. The token
stream IntStream.index()
will return the same value before and
after any getText()
call.
The rewriter only works on tokens that you have in the buffer and ignores the
current input cursor. If you are buffering tokens on-demand, calling
getText()
halfway through the input will only do rewrites for those
tokens in the first half of the file.
Since the operations are done lazily at getText()
-time, operations do
not screw up the token index values. That is, an insert operation at token
index i
does not change the index values for tokens
i
+1..n-1.
Because operations never actually alter the buffer, you may always get the original token stream back without undoing anything. Since the instructions are queued up, you can easily simulate transactions and roll back any changes if there is an error just by removing instructions. For example,
CharStream input = new ANTLRFileStream("input"); TLexer lex = new TLexer(input); CommonTokenStream tokens = new CommonTokenStream(lex); T parser = new T(tokens); TokenStreamRewriter rewriter = new TokenStreamRewriter(tokens); parser.startRule();
Then in the rules, you can execute (assuming rewriter is visible):
Token t,u; ... rewriter.insertAfter(t, "text to put after t");} rewriter.insertAfter(u, "text after u");} System.out.println(rewriter.getText());
You can also have multiple "instruction streams" and get multiple rewrites from a single pass over the input. Just name the instruction streams and use that name again when printing the buffer. This could be useful for generating a C file and also its header file--all from the same buffer:
rewriter.insertAfter("pass1", t, "text to put after t");} rewriter.insertAfter("pass2", u, "text after u");} System.out.println(rewriter.getText("pass1")); System.out.println(rewriter.getText("pass2"));
If you don't use named rewrite streams, a "default" stream is used as the first example shows.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescription(package private) class
Distinguish between insert after/before to do the "insert afters" first and then the "insert befores" at same index.(package private) class
(package private) class
I'm going to try replacing range from x..y with (y-x)+1 ReplaceOp instructions.class
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final String
Map String (program name) → Integer indexstatic final int
static final int
protected final Map
<String, List<TokenStreamRewriter.RewriteOperation>> You may have multiple, named streams of rewrite operations.protected final TokenStream
Our source stream -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprotected String
void
delete
(int index) void
delete
(int from, int to) void
void
void
void
void
void
deleteProgram
(String programName) Reset the program so that no instructions existprotected <T extends TokenStreamRewriter.RewriteOperation>
List<? extends T> getKindOfOps
(List<? extends TokenStreamRewriter.RewriteOperation> rewrites, Class<T> kind, int before) Get all operations before an index of a particular kindint
protected int
getLastRewriteTokenIndex
(String programName) protected List
<TokenStreamRewriter.RewriteOperation> getProgram
(String name) getText()
Return the text from the original tokens altered per the instructions given to this rewriter.Return the text from the original tokens altered per the instructions given to this rewriter in programName.Return the text associated with the tokens in the interval from the original token stream but with the alterations given to this rewriter.final TokenStream
private List
<TokenStreamRewriter.RewriteOperation> initializeProgram
(String name) void
insertAfter
(int index, Object text) void
insertAfter
(String programName, int index, Object text) void
insertAfter
(String programName, Token t, Object text) void
insertAfter
(Token t, Object text) void
insertBefore
(int index, Object text) void
insertBefore
(String programName, int index, Object text) void
insertBefore
(String programName, Token t, Object text) void
insertBefore
(Token t, Object text) protected Map
<Integer, TokenStreamRewriter.RewriteOperation> We need to combine operations and report invalid operations (like overlapping replaces that are not completed nested).void
void
void
void
void
void
void
rollback
(int instructionIndex) void
Rollback the instruction stream for a program so that the indicated instruction (via instructionIndex) is no longer in the stream.protected void
setLastRewriteTokenIndex
(String programName, int i)
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Field Details
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DEFAULT_PROGRAM_NAME
- See Also:
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PROGRAM_INIT_SIZE
public static final int PROGRAM_INIT_SIZE- See Also:
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MIN_TOKEN_INDEX
public static final int MIN_TOKEN_INDEX- See Also:
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tokens
Our source stream -
programs
You may have multiple, named streams of rewrite operations. I'm calling these things "programs." Maps String (name) → rewrite (List) -
lastRewriteTokenIndexes
Map String (program name) → Integer index
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Constructor Details
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TokenStreamRewriter
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Method Details
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getTokenStream
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rollback
public void rollback(int instructionIndex) -
rollback
Rollback the instruction stream for a program so that the indicated instruction (via instructionIndex) is no longer in the stream. UNTESTED! -
deleteProgram
public void deleteProgram() -
deleteProgram
Reset the program so that no instructions exist -
insertAfter
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insertAfter
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insertAfter
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insertAfter
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insertBefore
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insertBefore
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insertBefore
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insertBefore
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replace
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replace
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replace
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replace
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replace
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replace
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delete
public void delete(int index) -
delete
public void delete(int from, int to) -
delete
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delete
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delete
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delete
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getLastRewriteTokenIndex
public int getLastRewriteTokenIndex() -
getLastRewriteTokenIndex
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setLastRewriteTokenIndex
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getProgram
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initializeProgram
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getText
Return the text from the original tokens altered per the instructions given to this rewriter. -
getText
Return the text from the original tokens altered per the instructions given to this rewriter in programName. -
getText
Return the text associated with the tokens in the interval from the original token stream but with the alterations given to this rewriter. The interval refers to the indexes in the original token stream. We do not alter the token stream in any way, so the indexes and intervals are still consistent. Includes any operations done to the first and last token in the interval. So, if you did an insertBefore on the first token, you would get that insertion. The same is true if you do an insertAfter the stop token. -
getText
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reduceToSingleOperationPerIndex
protected Map<Integer,TokenStreamRewriter.RewriteOperation> reduceToSingleOperationPerIndex(List<TokenStreamRewriter.RewriteOperation> rewrites) We need to combine operations and report invalid operations (like overlapping replaces that are not completed nested). Inserts to same index need to be combined etc... Here are the cases: I.i.u I.j.v leave alone, nonoverlapping I.i.u I.i.v combine: Iivu R.i-j.u R.x-y.v | i-j in x-y delete first R R.i-j.u R.i-j.v delete first R R.i-j.u R.x-y.v | x-y in i-j ERROR R.i-j.u R.x-y.v | boundaries overlap ERROR Delete special case of replace (text==null): D.i-j.u D.x-y.v | boundaries overlap combine to max(min)..max(right) I.i.u R.x-y.v | i in (x+1)-y delete I (since insert before we're not deleting i) I.i.u R.x-y.v | i not in (x+1)-y leave alone, nonoverlapping R.x-y.v I.i.u | i in x-y ERROR R.x-y.v I.x.u R.x-y.uv (combine, delete I) R.x-y.v I.i.u | i not in x-y leave alone, nonoverlapping I.i.u = insert u before op @ index i R.x-y.u = replace x-y indexed tokens with u First we need to examine replaces. For any replace op: 1. wipe out any insertions before op within that range. 2. Drop any replace op before that is contained completely within that range. 3. Throw exception upon boundary overlap with any previous replace. Then we can deal with inserts: 1. for any inserts to same index, combine even if not adjacent. 2. for any prior replace with same left boundary, combine this insert with replace and delete this replace. 3. throw exception if index in same range as previous replace Don't actually delete; make op null in list. Easier to walk list. Later we can throw as we add to index → op map. Note that I.2 R.2-2 will wipe out I.2 even though, technically, the inserted stuff would be before the replace range. But, if you add tokens in front of a method body '{' and then delete the method body, I think the stuff before the '{' you added should disappear too. Return a map from token index to operation. -
catOpText
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getKindOfOps
protected <T extends TokenStreamRewriter.RewriteOperation> List<? extends T> getKindOfOps(List<? extends TokenStreamRewriter.RewriteOperation> rewrites, Class<T> kind, int before) Get all operations before an index of a particular kind
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