// © 2016 and later: Unicode, Inc. and others.

// License & terms of use: http://www.unicode.org/copyright.html

/*

*******************************************************************************

*   Copyright (C) 2010-2011, International Business Machines

*   Corporation and others.  All Rights Reserved.

*******************************************************************************

*   file name:  ucharstrieiterator.h

*   encoding:   UTF-8

*   tab size:   8 (not used)

*   indentation:4

*

*   created on: 2010nov15

*   created by: Markus W. Scherer

*/

#include "unicode/utypes.h"

#include "unicode/ucharstrie.h"

#include "unicode/unistr.h"

#include "uvectr32.h"

U_NAMESPACE_BEGIN

UCharsTrie::Iterator::Iterator(ConstChar16Ptr trieUChars, int32_t maxStringLength,

                               UErrorCode &errorCode)

        : uchars_(trieUChars),

          pos_(uchars_), initialPos_(uchars_),

          remainingMatchLength_(-1), initialRemainingMatchLength_(-1),

          skipValue_(false),

          maxLength_(maxStringLength), value_(0), stack_(nullptr) {

    if(U_FAILURE(errorCode)) {

        return;

    }

    // stack_ is a pointer so that it's easy to turn ucharstrie.h into

    // a public API header for which we would want it to depend only on

    // other public headers.

    // Unlike UCharsTrie itself, its Iterator performs memory allocations anyway

    // via the UnicodeString and UVector32 implementations, so this additional

    // cost is minimal.

    stack_=new UVector32(errorCode);

    if(stack_==nullptr) {

        errorCode=U_MEMORY_ALLOCATION_ERROR;

    }

}

UCharsTrie::Iterator::Iterator(const UCharsTrie &trie, int32_t maxStringLength,

                               UErrorCode &errorCode)

        : uchars_(trie.uchars_), pos_(trie.pos_), initialPos_(trie.pos_),

          remainingMatchLength_(trie.remainingMatchLength_),

          initialRemainingMatchLength_(trie.remainingMatchLength_),

          skipValue_(false),

          maxLength_(maxStringLength), value_(0), stack_(nullptr) {

    if(U_FAILURE(errorCode)) {

        return;

    }

    stack_=new UVector32(errorCode);

    if(U_FAILURE(errorCode)) {

        return;

    }

    if(stack_==nullptr) {

        errorCode=U_MEMORY_ALLOCATION_ERROR;

        return;

    }

    int32_t length=remainingMatchLength_;  // Actual remaining match length minus 1.

    if(length>=0) {

        // Pending linear-match node, append remaining UChars to str_.

        ++length;

        if(maxLength_>0 && length>maxLength_) {

            length=maxLength_;  // This will leave remainingMatchLength>=0 as a signal.

        }

        str_.append(pos_, length);

        pos_+=length;

        remainingMatchLength_-=length;

    }

}

UCharsTrie::Iterator::~Iterator() {

    delete stack_;

}

UCharsTrie::Iterator &

UCharsTrie::Iterator::reset() {

    pos_=initialPos_;

    remainingMatchLength_=initialRemainingMatchLength_;

    skipValue_=false;

    int32_t length=remainingMatchLength_+1;  // Remaining match length.

    if(maxLength_>0 && length>maxLength_) {

        length=maxLength_;

    }

    str_.truncate(length);

    pos_+=length;

    remainingMatchLength_-=length;

    stack_->setSize(0);

    return *this;

}

UBool

UCharsTrie::Iterator::hasNext() const { return pos_!=nullptr || !stack_->isEmpty(); }

UBool

UCharsTrie::Iterator::next(UErrorCode &errorCode) {

    if(U_FAILURE(errorCode)) {

        return false;

    }

    const char16_t *pos=pos_;

    if(pos==nullptr) {

        if(stack_->isEmpty()) {

            return false;

        }

        // Pop the state off the stack and continue with the next outbound edge of

        // the branch node.

        int32_t stackSize=stack_->size();

        int32_t length=stack_->elementAti(stackSize-1);

        pos=uchars_+stack_->elementAti(stackSize-2);

        stack_->setSize(stackSize-2);

        str_.truncate(length&0xffff);

        length = static_cast<int32_t>(static_cast<uint32_t>(length) >> 16);

        if(length>1) {

            pos=branchNext(pos, length, errorCode);

            if(pos==nullptr) {

                return true;  // Reached a final value.

            }

        } else {

            str_.append(*pos++);

        }

    }

    if(remainingMatchLength_>=0) {

        // We only get here if we started in a pending linear-match node

        // with more than maxLength remaining units.

        return truncateAndStop();

    }

    for(;;) {

        int32_t node=*pos++;

        if(node>=kMinValueLead) {

            if(skipValue_) {

                pos=skipNodeValue(pos, node);

                node&=kNodeTypeMask;

                skipValue_=false;

            } else {

                // Deliver value for the string so far.

                UBool isFinal = static_cast<UBool>(node >> 15);

                if(isFinal) {

                    value_=readValue(pos, node&0x7fff);

                } else {

                    value_=readNodeValue(pos, node);

                }

                if(isFinal || (maxLength_>0 && str_.length()==maxLength_)) {

                    pos_=nullptr;

                } else {

                    // We cannot skip the value right here because it shares its

                    // lead unit with a match node which we have to evaluate

                    // next time.

                    // Instead, keep pos_ on the node lead unit itself.

                    pos_=pos-1;

                    skipValue_=true;

                }

                return true;

            }

        }

        if(maxLength_>0 && str_.length()==maxLength_) {

            return truncateAndStop();

        }

        if(node<kMinLinearMatch) {

            if(node==0) {

                node=*pos++;

            }

            pos=branchNext(pos, node+1, errorCode);

            if(pos==nullptr) {

                return true;  // Reached a final value.

            }

        } else {

            // Linear-match node, append length units to str_.

            int32_t length=node-kMinLinearMatch+1;

            if(maxLength_>0 && str_.length()+length>maxLength_) {

                str_.append(pos, maxLength_-str_.length());

                return truncateAndStop();

            }

            str_.append(pos, length);

            pos+=length;

        }

    }

}

// Branch node, needs to take the first outbound edge and push state for the rest.

const char16_t *

UCharsTrie::Iterator::branchNext(const char16_t *pos, int32_t length, UErrorCode &errorCode) {

    while(length>kMaxBranchLinearSubNodeLength) {

        ++pos;  // ignore the comparison unit

        // Push state for the greater-or-equal edge.

        stack_->addElement(static_cast<int32_t>(skipDelta(pos) - uchars_), errorCode);

        stack_->addElement(((length-(length>>1))<<16)|str_.length(), errorCode);

        // Follow the less-than edge.

        length>>=1;

        pos=jumpByDelta(pos);

    }

    // List of key-value pairs where values are either final values or jump deltas.

    // Read the first (key, value) pair.

    char16_t trieUnit=*pos++;

    int32_t node=*pos++;

    UBool isFinal = static_cast<UBool>(node >> 15);

    int32_t value=readValue(pos, node&=0x7fff);

    pos=skipValue(pos, node);

    stack_->addElement(static_cast<int32_t>(pos - uchars_), errorCode);

    stack_->addElement(((length-1)<<16)|str_.length(), errorCode);

    str_.append(trieUnit);

    if(isFinal) {

        pos_=nullptr;

        value_=value;

        return nullptr;

    } else {

        return pos+value;

    }

}

U_NAMESPACE_END