--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/vendor/github.com/dlclark/regexp2/syntax/code.go	Sun Jul 23 13:18:53 2023 +0000
@@ -0,0 +1,274 @@
+package syntax
+
+import (
+	"bytes"
+	"fmt"
+	"math"
+)
+
+// similar to prog.go in the go regex package...also with comment 'may not belong in this package'
+
+// File provides operator constants for use by the Builder and the Machine.
+
+// Implementation notes:
+//
+// Regexps are built into RegexCodes, which contain an operation array,
+// a string table, and some constants.
+//
+// Each operation is one of the codes below, followed by the integer
+// operands specified for each op.
+//
+// Strings and sets are indices into a string table.
+
+type InstOp int
+
+const (
+	// 					    lef/back operands        description
+
+	Onerep    InstOp = 0 // lef,back char,min,max    a {n}
+	Notonerep        = 1 // lef,back char,min,max    .{n}
+	Setrep           = 2 // lef,back set,min,max     [\d]{n}
+
+	Oneloop    = 3 // lef,back char,min,max    a {,n}
+	Notoneloop = 4 // lef,back char,min,max    .{,n}
+	Setloop    = 5 // lef,back set,min,max     [\d]{,n}
+
+	Onelazy    = 6 // lef,back char,min,max    a {,n}?
+	Notonelazy = 7 // lef,back char,min,max    .{,n}?
+	Setlazy    = 8 // lef,back set,min,max     [\d]{,n}?
+
+	One    = 9  // lef      char            a
+	Notone = 10 // lef      char            [^a]
+	Set    = 11 // lef      set             [a-z\s]  \w \s \d
+
+	Multi = 12 // lef      string          abcd
+	Ref   = 13 // lef      group           \#
+
+	Bol         = 14 //                          ^
+	Eol         = 15 //                          $
+	Boundary    = 16 //                          \b
+	Nonboundary = 17 //                          \B
+	Beginning   = 18 //                          \A
+	Start       = 19 //                          \G
+	EndZ        = 20 //                          \Z
+	End         = 21 //                          \Z
+
+	Nothing = 22 //                          Reject!
+
+	// Primitive control structures
+
+	Lazybranch      = 23 // back     jump            straight first
+	Branchmark      = 24 // back     jump            branch first for loop
+	Lazybranchmark  = 25 // back     jump            straight first for loop
+	Nullcount       = 26 // back     val             set counter, null mark
+	Setcount        = 27 // back     val             set counter, make mark
+	Branchcount     = 28 // back     jump,limit      branch++ if zero<=c<limit
+	Lazybranchcount = 29 // back     jump,limit      same, but straight first
+	Nullmark        = 30 // back                     save position
+	Setmark         = 31 // back                     save position
+	Capturemark     = 32 // back     group           define group
+	Getmark         = 33 // back                     recall position
+	Setjump         = 34 // back                     save backtrack state
+	Backjump        = 35 //                          zap back to saved state
+	Forejump        = 36 //                          zap backtracking state
+	Testref         = 37 //                          backtrack if ref undefined
+	Goto            = 38 //          jump            just go
+
+	Prune = 39 //                          prune it baby
+	Stop  = 40 //                          done!
+
+	ECMABoundary    = 41 //                          \b
+	NonECMABoundary = 42 //                          \B
+
+	// Modifiers for alternate modes
+
+	Mask  = 63  // Mask to get unmodified ordinary operator
+	Rtl   = 64  // bit to indicate that we're reverse scanning.
+	Back  = 128 // bit to indicate that we're backtracking.
+	Back2 = 256 // bit to indicate that we're backtracking on a second branch.
+	Ci    = 512 // bit to indicate that we're case-insensitive.
+)
+
+type Code struct {
+	Codes       []int       // the code
+	Strings     [][]rune    // string table
+	Sets        []*CharSet  //character set table
+	TrackCount  int         // how many instructions use backtracking
+	Caps        map[int]int // mapping of user group numbers -> impl group slots
+	Capsize     int         // number of impl group slots
+	FcPrefix    *Prefix     // the set of candidate first characters (may be null)
+	BmPrefix    *BmPrefix   // the fixed prefix string as a Boyer-Moore machine (may be null)
+	Anchors     AnchorLoc   // the set of zero-length start anchors (RegexFCD.Bol, etc)
+	RightToLeft bool        // true if right to left
+}
+
+func opcodeBacktracks(op InstOp) bool {
+	op &= Mask
+
+	switch op {
+	case Oneloop, Notoneloop, Setloop, Onelazy, Notonelazy, Setlazy, Lazybranch, Branchmark, Lazybranchmark,
+		Nullcount, Setcount, Branchcount, Lazybranchcount, Setmark, Capturemark, Getmark, Setjump, Backjump,
+		Forejump, Goto:
+		return true
+
+	default:
+		return false
+	}
+}
+
+func opcodeSize(op InstOp) int {
+	op &= Mask
+
+	switch op {
+	case Nothing, Bol, Eol, Boundary, Nonboundary, ECMABoundary, NonECMABoundary, Beginning, Start, EndZ,
+		End, Nullmark, Setmark, Getmark, Setjump, Backjump, Forejump, Stop:
+		return 1
+
+	case One, Notone, Multi, Ref, Testref, Goto, Nullcount, Setcount, Lazybranch, Branchmark, Lazybranchmark,
+		Prune, Set:
+		return 2
+
+	case Capturemark, Branchcount, Lazybranchcount, Onerep, Notonerep, Oneloop, Notoneloop, Onelazy, Notonelazy,
+		Setlazy, Setrep, Setloop:
+		return 3
+
+	default:
+		panic(fmt.Errorf("Unexpected op code: %v", op))
+	}
+}
+
+var codeStr = []string{
+	"Onerep", "Notonerep", "Setrep",
+	"Oneloop", "Notoneloop", "Setloop",
+	"Onelazy", "Notonelazy", "Setlazy",
+	"One", "Notone", "Set",
+	"Multi", "Ref",
+	"Bol", "Eol", "Boundary", "Nonboundary", "Beginning", "Start", "EndZ", "End",
+	"Nothing",
+	"Lazybranch", "Branchmark", "Lazybranchmark",
+	"Nullcount", "Setcount", "Branchcount", "Lazybranchcount",
+	"Nullmark", "Setmark", "Capturemark", "Getmark",
+	"Setjump", "Backjump", "Forejump", "Testref", "Goto",
+	"Prune", "Stop",
+	"ECMABoundary", "NonECMABoundary",
+}
+
+func operatorDescription(op InstOp) string {
+	desc := codeStr[op&Mask]
+	if (op & Ci) != 0 {
+		desc += "-Ci"
+	}
+	if (op & Rtl) != 0 {
+		desc += "-Rtl"
+	}
+	if (op & Back) != 0 {
+		desc += "-Back"
+	}
+	if (op & Back2) != 0 {
+		desc += "-Back2"
+	}
+
+	return desc
+}
+
+// OpcodeDescription is a humman readable string of the specific offset
+func (c *Code) OpcodeDescription(offset int) string {
+	buf := &bytes.Buffer{}
+
+	op := InstOp(c.Codes[offset])
+	fmt.Fprintf(buf, "%06d ", offset)
+
+	if opcodeBacktracks(op & Mask) {
+		buf.WriteString("*")
+	} else {
+		buf.WriteString(" ")
+	}
+	buf.WriteString(operatorDescription(op))
+	buf.WriteString("(")
+	op &= Mask
+
+	switch op {
+	case One, Notone, Onerep, Notonerep, Oneloop, Notoneloop, Onelazy, Notonelazy:
+		buf.WriteString("Ch = ")
+		buf.WriteString(CharDescription(rune(c.Codes[offset+1])))
+
+	case Set, Setrep, Setloop, Setlazy:
+		buf.WriteString("Set = ")
+		buf.WriteString(c.Sets[c.Codes[offset+1]].String())
+
+	case Multi:
+		fmt.Fprintf(buf, "String = %s", string(c.Strings[c.Codes[offset+1]]))
+
+	case Ref, Testref:
+		fmt.Fprintf(buf, "Index = %d", c.Codes[offset+1])
+
+	case Capturemark:
+		fmt.Fprintf(buf, "Index = %d", c.Codes[offset+1])
+		if c.Codes[offset+2] != -1 {
+			fmt.Fprintf(buf, ", Unindex = %d", c.Codes[offset+2])
+		}
+
+	case Nullcount, Setcount:
+		fmt.Fprintf(buf, "Value = %d", c.Codes[offset+1])
+
+	case Goto, Lazybranch, Branchmark, Lazybranchmark, Branchcount, Lazybranchcount:
+		fmt.Fprintf(buf, "Addr = %d", c.Codes[offset+1])
+	}
+
+	switch op {
+	case Onerep, Notonerep, Oneloop, Notoneloop, Onelazy, Notonelazy, Setrep, Setloop, Setlazy:
+		buf.WriteString(", Rep = ")
+		if c.Codes[offset+2] == math.MaxInt32 {
+			buf.WriteString("inf")
+		} else {
+			fmt.Fprintf(buf, "%d", c.Codes[offset+2])
+		}
+
+	case Branchcount, Lazybranchcount:
+		buf.WriteString(", Limit = ")
+		if c.Codes[offset+2] == math.MaxInt32 {
+			buf.WriteString("inf")
+		} else {
+			fmt.Fprintf(buf, "%d", c.Codes[offset+2])
+		}
+
+	}
+
+	buf.WriteString(")")
+
+	return buf.String()
+}
+
+func (c *Code) Dump() string {
+	buf := &bytes.Buffer{}
+
+	if c.RightToLeft {
+		fmt.Fprintln(buf, "Direction:  right-to-left")
+	} else {
+		fmt.Fprintln(buf, "Direction:  left-to-right")
+	}
+	if c.FcPrefix == nil {
+		fmt.Fprintln(buf, "Firstchars: n/a")
+	} else {
+		fmt.Fprintf(buf, "Firstchars: %v\n", c.FcPrefix.PrefixSet.String())
+	}
+
+	if c.BmPrefix == nil {
+		fmt.Fprintln(buf, "Prefix:     n/a")
+	} else {
+		fmt.Fprintf(buf, "Prefix:     %v\n", Escape(c.BmPrefix.String()))
+	}
+
+	fmt.Fprintf(buf, "Anchors:    %v\n", c.Anchors)
+	fmt.Fprintln(buf)
+
+	if c.BmPrefix != nil {
+		fmt.Fprintln(buf, "BoyerMoore:")
+		fmt.Fprintln(buf, c.BmPrefix.Dump("    "))
+	}
+	for i := 0; i < len(c.Codes); i += opcodeSize(InstOp(c.Codes[i])) {
+		fmt.Fprintln(buf, c.OpcodeDescription(i))
+	}
+
+	return buf.String()
+}