// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
//
//  regexcmp.h
//
//  Copyright (C) 2002-2016, International Business Machines Corporation and others.
//  All Rights Reserved.
//
//  This file contains declarations for the class RegexCompile
//
//  This class is internal to the regular expression implementation.
//  For the public Regular Expression API, see the file "unicode/regex.h"
//


#ifndef REGEXCMP_H
#define REGEXCMP_H

#include "unicode/utypes.h"
#if !UCONFIG_NO_REGULAR_EXPRESSIONS

#include "unicode/parseerr.h"
#include "unicode/uniset.h"
#include "unicode/uobject.h"
#include "unicode/utext.h"
#include "uhash.h"
#include "uvector.h"
#include "uvectr32.h"



U_NAMESPACE_BEGIN


//--------------------------------------------------------------------------------
//
//  class RegexCompile    Contains the regular expression compiler.
//
//--------------------------------------------------------------------------------
class   RegexPattern;


class U_I18N_API RegexCompile : public UMemory {
public:

    enum {
        kStackSize = 100            // The size of the state stack for
    };                              //   pattern parsing.  Corresponds roughly
                                    //   to the depth of parentheses nesting
                                    //   that is allowed in the rules.

    struct RegexPatternChar {
        UChar32             fChar;
        UBool               fQuoted;
    };

    RegexCompile(RegexPattern *rp, UErrorCode &e);

    void       compile(const UnicodeString &pat, UParseError &pp, UErrorCode &e);
    void       compile(UText *pat, UParseError &pp, UErrorCode &e);
    

    virtual    ~RegexCompile();

    void        nextChar(RegexPatternChar &c);      // Get the next char from the input stream.


    // Categories of parentheses in pattern.
    //   The category is saved in the compile-time parentheses stack frame, and
    //   determines the code to be generated when the matching close ) is encountered.
    enum EParenClass {
        plain        = -1,               // No special handling
        capturing    = -2,
        atomic       = -3,
        lookAhead    = -4,
        negLookAhead = -5,
        flags        = -6,
        lookBehind   = -7,
        lookBehindN  = -8
    };

private:


    UBool       doParseActions(int32_t a);
    void        error(UErrorCode e);                   // error reporting convenience function.

    UChar32     nextCharLL();
    UChar32     peekCharLL();
    UnicodeSet  *scanProp();
    UnicodeSet  *scanPosixProp();
    void        handleCloseParen();
    int32_t     blockTopLoc(UBool reserve);          // Locate a position in the compiled pattern
                                                     //  at the top of the just completed block
                                                     //  or operation, and optionally ensure that
                                                     //  there is space to add an opcode there.
    void        compileSet(UnicodeSet *theSet);      // Generate the compiled pattern for
                                                     //   a reference to a UnicodeSet.
    void        compileInterval(int32_t InitOp,      // Generate the code for a {min,max} quantifier.
                               int32_t LoopOp);
    UBool       compileInlineInterval();             // Generate inline code for a {min,max} quantifier
    void        literalChar(UChar32 c);              // Compile a literal char
    void        fixLiterals(UBool split=false);      // Generate code for pending literal characters.
    void        insertOp(int32_t where);             // Open up a slot for a new op in the
                                                     //   generated code at the specified location.
    void        appendOp(int32_t op);                // Append a new op to the compiled pattern.
    void        appendOp(int32_t type, int32_t val); // Build & append a new op to the compiled pattern.
    int32_t     buildOp(int32_t type, int32_t val);  // Construct a new pcode instruction.
    int32_t     allocateData(int32_t size);          // Allocate space in the matcher data area.
                                                     //   Return index of the newly allocated data.
    int32_t     allocateStackData(int32_t size);     // Allocate space in the match back-track stack frame.
                                                     //   Return offset index in the frame.
    int32_t     minMatchLength(int32_t start,
                               int32_t end);
    int32_t     maxMatchLength(int32_t start,
                               int32_t end);
    void        matchStartType();
    void        stripNOPs();

    void        setEval(int32_t op);
    void        setPushOp(int32_t op);
    UChar32     scanNamedChar();
    UnicodeSet *createSetForProperty(const UnicodeString &propName, UBool negated);

public:   // Public for testing only.
    static void U_EXPORT2 findCaseInsensitiveStarters(UChar32 c, UnicodeSet *starterChars);
private:


    UErrorCode                    *fStatus;
    RegexPattern                  *fRXPat;
    UParseError                   *fParseErr;

    //
    //  Data associated with low level character scanning
    //
    int64_t                       fScanIndex;        // Index of current character being processed
                                                     //   in the rule input string.
    UBool                         fQuoteMode;        // Scan is in a \Q...\E quoted region
    UBool                         fInBackslashQuote; // Scan is between a '\' and the following char.
    UBool                         fEOLComments;      // When scan is just after '(?',  inhibit #... to
                                                     //   end of line comments, in favor of (?#...) comments.
    int64_t                       fLineNum;          // Line number in input file.
    int64_t                       fCharNum;          // Char position within the line.
    UChar32                       fLastChar;         // Previous char, needed to count CR-LF
                                                     //   as a single line, not two.
    UChar32                       fPeekChar;         // Saved char, if we've scanned ahead.


    RegexPatternChar              fC;                // Current char for parse state machine
                                                     //   processing.

    uint16_t                      fStack[kStackSize];  // State stack, holds state pushes
    int32_t                       fStackPtr;           //  and pops as specified in the state
                                                       //  transition rules.

    //
    //  Data associated with the generation of the pcode for the match engine
    //
    int32_t                       fModeFlags;        // Match Flags.  (Case Insensitive, etc.)
                                                     //   Always has high bit (31) set so that flag values
                                                     //   on the paren stack are distinguished from relocatable
                                                     //   pcode addresses.
    int32_t                       fNewModeFlags;     // New flags, while compiling (?i, holds state
                                                     //   until last flag is scanned.
    UBool                         fSetModeFlag;      // true for (?ismx, false for (?-ismx

    UnicodeString                 fLiteralChars;     // Literal chars or strings from the pattern are accumulated here.
                                                     //   Once completed, meaning that some non-literal pattern
                                                     //   construct is encountered, the appropriate opcodes
                                                     //   to match the literal will be generated, and this
                                                     //   string will be cleared.

    int64_t                       fPatternLength;    // Length of the input pattern string.
    
    UVector32                     fParenStack;       // parentheses stack.  Each frame consists of
                                                     //   the positions of compiled pattern operations
                                                     //   needing fixup, followed by negative value.  The
                                                     //   first entry in each frame is the position of the
                                                     //   spot reserved for use when a quantifier
                                                     //   needs to add a SAVE at the start of a (block)
                                                     //   The negative value (-1, -2,...) indicates
                                                     //   the kind of paren that opened the frame.  Some
                                                     //   need special handling on close.


    int32_t                       fMatchOpenParen;   // The position in the compiled pattern
                                                     //   of the slot reserved for a state save
                                                     //   at the start of the most recently processed
                                                     //   parenthesized block. Updated when processing
                                                     //   a close to the location for the corresponding open.

    int32_t                       fMatchCloseParen;  // The position in the pattern of the first
                                                     //   location after the most recently processed
                                                     //   parenthesized block.

    int32_t                       fIntervalLow;      // {lower, upper} interval quantifier values.
    int32_t                       fIntervalUpper;    // Placed here temporarily, when pattern is
                                                     //   initially scanned.  Each new interval
                                                     //   encountered overwrites these values.
                                                     //   -1 for the upper interval value means none
                                                     //   was specified (unlimited occurrences.)

    UStack                        fSetStack;         // Stack of UnicodeSets, used while evaluating
                                                     //   (at compile time) set expressions within
                                                     //   the pattern.
    UStack                        fSetOpStack;       // Stack of pending set operators (&&, --, union)

    UChar32                       fLastSetLiteral;   // The last single code point added to a set.
                                                     //   needed when "-y" is scanned, and we need
                                                     //   to turn "x-y" into a range.

    UnicodeString                *fCaptureName;      // Named Capture, the group name is built up
                                                     //   in this string while being scanned.
};

// Constant values to be pushed onto fSetOpStack while scanning & evaluating [set expressions]
//   The high 16 bits are the operator precedence, and the low 16 are a code for the operation itself.

enum SetOperations {
    setStart         = 0 << 16 | 1,
    setEnd           = 1 << 16 | 2,
    setNegation      = 2 << 16 | 3,
    setCaseClose     = 2 << 16 | 9,
    setDifference2   = 3 << 16 | 4,    // '--' set difference operator
    setIntersection2 = 3 << 16 | 5,    // '&&' set intersection operator
    setUnion         = 4 << 16 | 6,    // implicit union of adjacent items
    setDifference1   = 4 << 16 | 7,    // '-', single dash difference op, for compatibility with old UnicodeSet.
    setIntersection1 = 4 << 16 | 8     // '&', single amp intersection op, for compatibility with old UnicodeSet.
    };

U_NAMESPACE_END
#endif   // !UCONFIG_NO_REGULAR_EXPRESSIONS
#endif   // REGEXCMP_H
