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