michael@0: /*
michael@0: *******************************************************************************
michael@0: *   Copyright (C) 2010-2012, International Business Machines
michael@0: *   Corporation and others.  All Rights Reserved.
michael@0: *******************************************************************************
michael@0: *   file name:  bytestrieiterator.cpp
michael@0: *   encoding:   US-ASCII
michael@0: *   tab size:   8 (not used)
michael@0: *   indentation:4
michael@0: *
michael@0: *   created on: 2010nov03
michael@0: *   created by: Markus W. Scherer
michael@0: */
michael@0: 
michael@0: #include "unicode/utypes.h"
michael@0: #include "unicode/bytestrie.h"
michael@0: #include "unicode/stringpiece.h"
michael@0: #include "charstr.h"
michael@0: #include "uvectr32.h"
michael@0: 
michael@0: U_NAMESPACE_BEGIN
michael@0: 
michael@0: BytesTrie::Iterator::Iterator(const void *trieBytes, int32_t maxStringLength,
michael@0:                               UErrorCode &errorCode)
michael@0:         : bytes_(static_cast<const uint8_t *>(trieBytes)),
michael@0:           pos_(bytes_), initialPos_(bytes_),
michael@0:           remainingMatchLength_(-1), initialRemainingMatchLength_(-1),
michael@0:           str_(NULL), maxLength_(maxStringLength), value_(0), stack_(NULL) {
michael@0:     if(U_FAILURE(errorCode)) {
michael@0:         return;
michael@0:     }
michael@0:     // str_ and stack_ are pointers so that it's easy to turn bytestrie.h into
michael@0:     // a public API header for which we would want it to depend only on
michael@0:     // other public headers.
michael@0:     // Unlike BytesTrie itself, its Iterator performs memory allocations anyway
michael@0:     // via the CharString and UVector32 implementations, so this additional
michael@0:     // cost is minimal.
michael@0:     str_=new CharString();
michael@0:     stack_=new UVector32(errorCode);
michael@0:     if(U_SUCCESS(errorCode) && (str_==NULL || stack_==NULL)) {
michael@0:         errorCode=U_MEMORY_ALLOCATION_ERROR;
michael@0:     }
michael@0: }
michael@0: 
michael@0: BytesTrie::Iterator::Iterator(const BytesTrie &trie, int32_t maxStringLength,
michael@0:                               UErrorCode &errorCode)
michael@0:         : bytes_(trie.bytes_), pos_(trie.pos_), initialPos_(trie.pos_),
michael@0:           remainingMatchLength_(trie.remainingMatchLength_),
michael@0:           initialRemainingMatchLength_(trie.remainingMatchLength_),
michael@0:           str_(NULL), maxLength_(maxStringLength), value_(0), stack_(NULL) {
michael@0:     if(U_FAILURE(errorCode)) {
michael@0:         return;
michael@0:     }
michael@0:     str_=new CharString();
michael@0:     stack_=new UVector32(errorCode);
michael@0:     if(U_FAILURE(errorCode)) {
michael@0:         return;
michael@0:     }
michael@0:     if(str_==NULL || stack_==NULL) {
michael@0:         errorCode=U_MEMORY_ALLOCATION_ERROR;
michael@0:         return;
michael@0:     }
michael@0:     int32_t length=remainingMatchLength_;  // Actual remaining match length minus 1.
michael@0:     if(length>=0) {
michael@0:         // Pending linear-match node, append remaining bytes to str_.
michael@0:         ++length;
michael@0:         if(maxLength_>0 && length>maxLength_) {
michael@0:             length=maxLength_;  // This will leave remainingMatchLength>=0 as a signal.
michael@0:         }
michael@0:         str_->append(reinterpret_cast<const char *>(pos_), length, errorCode);
michael@0:         pos_+=length;
michael@0:         remainingMatchLength_-=length;
michael@0:     }
michael@0: }
michael@0: 
michael@0: BytesTrie::Iterator::~Iterator() {
michael@0:     delete str_;
michael@0:     delete stack_;
michael@0: }
michael@0: 
michael@0: BytesTrie::Iterator &
michael@0: BytesTrie::Iterator::reset() {
michael@0:     pos_=initialPos_;
michael@0:     remainingMatchLength_=initialRemainingMatchLength_;
michael@0:     int32_t length=remainingMatchLength_+1;  // Remaining match length.
michael@0:     if(maxLength_>0 && length>maxLength_) {
michael@0:         length=maxLength_;
michael@0:     }
michael@0:     str_->truncate(length);
michael@0:     pos_+=length;
michael@0:     remainingMatchLength_-=length;
michael@0:     stack_->setSize(0);
michael@0:     return *this;
michael@0: }
michael@0: 
michael@0: UBool
michael@0: BytesTrie::Iterator::hasNext() const { return pos_!=NULL || !stack_->isEmpty(); }
michael@0: 
michael@0: UBool
michael@0: BytesTrie::Iterator::next(UErrorCode &errorCode) {
michael@0:     if(U_FAILURE(errorCode)) {
michael@0:         return FALSE;
michael@0:     }
michael@0:     const uint8_t *pos=pos_;
michael@0:     if(pos==NULL) {
michael@0:         if(stack_->isEmpty()) {
michael@0:             return FALSE;
michael@0:         }
michael@0:         // Pop the state off the stack and continue with the next outbound edge of
michael@0:         // the branch node.
michael@0:         int32_t stackSize=stack_->size();
michael@0:         int32_t length=stack_->elementAti(stackSize-1);
michael@0:         pos=bytes_+stack_->elementAti(stackSize-2);
michael@0:         stack_->setSize(stackSize-2);
michael@0:         str_->truncate(length&0xffff);
michael@0:         length=(int32_t)((uint32_t)length>>16);
michael@0:         if(length>1) {
michael@0:             pos=branchNext(pos, length, errorCode);
michael@0:             if(pos==NULL) {
michael@0:                 return TRUE;  // Reached a final value.
michael@0:             }
michael@0:         } else {
michael@0:             str_->append((char)*pos++, errorCode);
michael@0:         }
michael@0:     }
michael@0:     if(remainingMatchLength_>=0) {
michael@0:         // We only get here if we started in a pending linear-match node
michael@0:         // with more than maxLength remaining bytes.
michael@0:         return truncateAndStop();
michael@0:     }
michael@0:     for(;;) {
michael@0:         int32_t node=*pos++;
michael@0:         if(node>=kMinValueLead) {
michael@0:             // Deliver value for the byte sequence so far.
michael@0:             UBool isFinal=(UBool)(node&kValueIsFinal);
michael@0:             value_=readValue(pos, node>>1);
michael@0:             if(isFinal || (maxLength_>0 && str_->length()==maxLength_)) {
michael@0:                 pos_=NULL;
michael@0:             } else {
michael@0:                 pos_=skipValue(pos, node);
michael@0:             }
michael@0:             sp_.set(str_->data(), str_->length());
michael@0:             return TRUE;
michael@0:         }
michael@0:         if(maxLength_>0 && str_->length()==maxLength_) {
michael@0:             return truncateAndStop();
michael@0:         }
michael@0:         if(node<kMinLinearMatch) {
michael@0:             if(node==0) {
michael@0:                 node=*pos++;
michael@0:             }
michael@0:             pos=branchNext(pos, node+1, errorCode);
michael@0:             if(pos==NULL) {
michael@0:                 return TRUE;  // Reached a final value.
michael@0:             }
michael@0:         } else {
michael@0:             // Linear-match node, append length bytes to str_.
michael@0:             int32_t length=node-kMinLinearMatch+1;
michael@0:             if(maxLength_>0 && str_->length()+length>maxLength_) {
michael@0:                 str_->append(reinterpret_cast<const char *>(pos),
michael@0:                             maxLength_-str_->length(), errorCode);
michael@0:                 return truncateAndStop();
michael@0:             }
michael@0:             str_->append(reinterpret_cast<const char *>(pos), length, errorCode);
michael@0:             pos+=length;
michael@0:         }
michael@0:     }
michael@0: }
michael@0: 
michael@0: UBool
michael@0: BytesTrie::Iterator::truncateAndStop() {
michael@0:     pos_=NULL;
michael@0:     sp_.set(str_->data(), str_->length());
michael@0:     value_=-1;  // no real value for str
michael@0:     return TRUE;
michael@0: }
michael@0: 
michael@0: // Branch node, needs to take the first outbound edge and push state for the rest.
michael@0: const uint8_t *
michael@0: BytesTrie::Iterator::branchNext(const uint8_t *pos, int32_t length, UErrorCode &errorCode) {
michael@0:     while(length>kMaxBranchLinearSubNodeLength) {
michael@0:         ++pos;  // ignore the comparison byte
michael@0:         // Push state for the greater-or-equal edge.
michael@0:         stack_->addElement((int32_t)(skipDelta(pos)-bytes_), errorCode);
michael@0:         stack_->addElement(((length-(length>>1))<<16)|str_->length(), errorCode);
michael@0:         // Follow the less-than edge.
michael@0:         length>>=1;
michael@0:         pos=jumpByDelta(pos);
michael@0:     }
michael@0:     // List of key-value pairs where values are either final values or jump deltas.
michael@0:     // Read the first (key, value) pair.
michael@0:     uint8_t trieByte=*pos++;
michael@0:     int32_t node=*pos++;
michael@0:     UBool isFinal=(UBool)(node&kValueIsFinal);
michael@0:     int32_t value=readValue(pos, node>>1);
michael@0:     pos=skipValue(pos, node);
michael@0:     stack_->addElement((int32_t)(pos-bytes_), errorCode);
michael@0:     stack_->addElement(((length-1)<<16)|str_->length(), errorCode);
michael@0:     str_->append((char)trieByte, errorCode);
michael@0:     if(isFinal) {
michael@0:         pos_=NULL;
michael@0:         sp_.set(str_->data(), str_->length());
michael@0:         value_=value;
michael@0:         return NULL;
michael@0:     } else {
michael@0:         return pos+value;
michael@0:     }
michael@0: }
michael@0: 
michael@0: U_NAMESPACE_END