Imported Upstream version 1.4upstream/1.4

1 files changed, 0 insertions, 151 deletions

diff --git a/src/pkg/regexp/syntax/simplify.go b/src/pkg/regexp/syntax/simplify.go
deleted file mode 100644
index 72390417b..000000000
--- a/src/pkg/regexp/syntax/simplify.go
+++ /dev/null
@@ -1,151 +0,0 @@
-// Copyright 2011 The Go Authors.  All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package syntax
-
-// Simplify returns a regexp equivalent to re but without counted repetitions
-// and with various other simplifications, such as rewriting /(?:a+)+/ to /a+/.
-// The resulting regexp will execute correctly but its string representation
-// will not produce the same parse tree, because capturing parentheses
-// may have been duplicated or removed.  For example, the simplified form
-// for /(x){1,2}/ is /(x)(x)?/ but both parentheses capture as $1.
-// The returned regexp may share structure with or be the original.
-func (re *Regexp) Simplify() *Regexp {
-	if re == nil {
-		return nil
-	}
-	switch re.Op {
-	case OpCapture, OpConcat, OpAlternate:
-		// Simplify children, building new Regexp if children change.
-		nre := re
-		for i, sub := range re.Sub {
-			nsub := sub.Simplify()
-			if nre == re && nsub != sub {
-				// Start a copy.
-				nre = new(Regexp)
-				*nre = *re
-				nre.Rune = nil
-				nre.Sub = append(nre.Sub0[:0], re.Sub[:i]...)
-			}
-			if nre != re {
-				nre.Sub = append(nre.Sub, nsub)
-			}
-		}
-		return nre
-
-	case OpStar, OpPlus, OpQuest:
-		sub := re.Sub[0].Simplify()
-		return simplify1(re.Op, re.Flags, sub, re)
-
-	case OpRepeat:
-		// Special special case: x{0} matches the empty string
-		// and doesn't even need to consider x.
-		if re.Min == 0 && re.Max == 0 {
-			return &Regexp{Op: OpEmptyMatch}
-		}
-
-		// The fun begins.
-		sub := re.Sub[0].Simplify()
-
-		// x{n,} means at least n matches of x.
-		if re.Max == -1 {
-			// Special case: x{0,} is x*.
-			if re.Min == 0 {
-				return simplify1(OpStar, re.Flags, sub, nil)
-			}
-
-			// Special case: x{1,} is x+.
-			if re.Min == 1 {
-				return simplify1(OpPlus, re.Flags, sub, nil)
-			}
-
-			// General case: x{4,} is xxxx+.
-			nre := &Regexp{Op: OpConcat}
-			nre.Sub = nre.Sub0[:0]
-			for i := 0; i < re.Min-1; i++ {
-				nre.Sub = append(nre.Sub, sub)
-			}
-			nre.Sub = append(nre.Sub, simplify1(OpPlus, re.Flags, sub, nil))
-			return nre
-		}
-
-		// Special case x{0} handled above.
-
-		// Special case: x{1} is just x.
-		if re.Min == 1 && re.Max == 1 {
-			return sub
-		}
-
-		// General case: x{n,m} means n copies of x and m copies of x?
-		// The machine will do less work if we nest the final m copies,
-		// so that x{2,5} = xx(x(x(x)?)?)?
-
-		// Build leading prefix: xx.
-		var prefix *Regexp
-		if re.Min > 0 {
-			prefix = &Regexp{Op: OpConcat}
-			prefix.Sub = prefix.Sub0[:0]
-			for i := 0; i < re.Min; i++ {
-				prefix.Sub = append(prefix.Sub, sub)
-			}
-		}
-
-		// Build and attach suffix: (x(x(x)?)?)?
-		if re.Max > re.Min {
-			suffix := simplify1(OpQuest, re.Flags, sub, nil)
-			for i := re.Min + 1; i < re.Max; i++ {
-				nre2 := &Regexp{Op: OpConcat}
-				nre2.Sub = append(nre2.Sub0[:0], sub, suffix)
-				suffix = simplify1(OpQuest, re.Flags, nre2, nil)
-			}
-			if prefix == nil {
-				return suffix
-			}
-			prefix.Sub = append(prefix.Sub, suffix)
-		}
-		if prefix != nil {
-			return prefix
-		}
-
-		// Some degenerate case like min > max or min < max < 0.
-		// Handle as impossible match.
-		return &Regexp{Op: OpNoMatch}
-	}
-
-	return re
-}
-
-// simplify1 implements Simplify for the unary OpStar,
-// OpPlus, and OpQuest operators.  It returns the simple regexp
-// equivalent to
-//
-//	Regexp{Op: op, Flags: flags, Sub: {sub}}
-//
-// under the assumption that sub is already simple, and
-// without first allocating that structure.  If the regexp
-// to be returned turns out to be equivalent to re, simplify1
-// returns re instead.
-//
-// simplify1 is factored out of Simplify because the implementation
-// for other operators generates these unary expressions.
-// Letting them call simplify1 makes sure the expressions they
-// generate are simple.
-func simplify1(op Op, flags Flags, sub, re *Regexp) *Regexp {
-	// Special case: repeat the empty string as much as
-	// you want, but it's still the empty string.
-	if sub.Op == OpEmptyMatch {
-		return sub
-	}
-	// The operators are idempotent if the flags match.
-	if op == sub.Op && flags&NonGreedy == sub.Flags&NonGreedy {
-		return sub
-	}
-	if re != nil && re.Op == op && re.Flags&NonGreedy == flags&NonGreedy && sub == re.Sub[0] {
-		return re
-	}
-
-	re = &Regexp{Op: op, Flags: flags}
-	re.Sub = append(re.Sub0[:0], sub)
-	return re
-}