Code:
/ DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Regex / System / Text / RegularExpressions / RegexReplacement.cs / 1 / RegexReplacement.cs
//------------------------------------------------------------------------------ //// Copyright (c) Microsoft Corporation. All rights reserved. // //----------------------------------------------------------------------------- // The RegexReplacement class represents a substitution string for // use when using regexs to search/replace, etc. It's logically // a sequence intermixed (1) constant strings and (2) group numbers. namespace System.Text.RegularExpressions { using System.Collections; internal sealed class RegexReplacement { /* * Since RegexReplacement shares the same parser as Regex, * the constructor takes a RegexNode which is a concatenation * of constant strings and backreferences. */ internal RegexReplacement(String rep, RegexNode concat, Hashtable _caps) { StringBuilder sb; ArrayList strings; ArrayList rules; int slot; _rep = rep; if (concat.Type() != RegexNode.Concatenate) throw new ArgumentException(SR.GetString(SR.ReplacementError)); sb = new StringBuilder(); strings = new ArrayList(); rules = new ArrayList(); for (int i = 0; i < concat.ChildCount(); i++) { RegexNode child = concat.Child(i); switch (child.Type()) { case RegexNode.Multi: sb.Append(child._str); break; case RegexNode.One: sb.Append(child._ch); break; case RegexNode.Ref: if (sb.Length > 0) { rules.Add(strings.Count); strings.Add(sb.ToString()); sb.Length = 0; } slot = child._m; if (_caps != null && slot >= 0) slot = (int)_caps[slot]; rules.Add(-Specials - 1 - slot); break; default: throw new ArgumentException(SR.GetString(SR.ReplacementError)); } } if (sb.Length > 0) { rules.Add(strings.Count); strings.Add(sb.ToString()); } _strings = strings; _rules = rules; } internal String _rep; internal ArrayList _strings; // table of string constants internal ArrayList _rules; // negative -> group #, positive -> string # // constants for special insertion patterns internal const int Specials = 4; internal const int LeftPortion = -1; internal const int RightPortion = -2; internal const int LastGroup = -3; internal const int WholeString = -4; /* * Given a Match, emits into the StringBuilder the evaluated * substitution pattern. */ private void ReplacementImpl(StringBuilder sb, Match match) { for (int i = 0; i < _rules.Count; i++) { int r = (int) _rules[i]; if (r >= 0) sb.Append((string) _strings[r]); else if (r < -Specials) sb.Append(match.GroupToStringImpl(-Specials - 1 - r)); else { switch (-Specials - 1 - r) { case LeftPortion: sb.Append(match.GetLeftSubstring()); break; case RightPortion: sb.Append(match.GetRightSubstring()); break; case LastGroup: sb.Append(match.LastGroupToStringImpl()); break; case WholeString: sb.Append(match.GetOriginalString()); break; } } } } /* * The original pattern string */ internal String Pattern { get { return _rep; } } /* * Returns the replacement result for a single match */ internal String Replacement(Match match) { StringBuilder sb = new StringBuilder(); ReplacementImpl(sb, match); return sb.ToString(); } /* * Three very similar algorithms appear below: replace (pattern), * replace (evaluator), and split. */ /* * Replaces all ocurrances of the regex in the string with the * replacement pattern. * * Note that the special case of no matches is handled on its own: * with no matches, the input string is returned unchanged. * The right-to-left case is split out because StringBuilder * doesn't handle right-to-left string building directly very well. */ internal String Replace(Regex regex, String input, int count, int startat) { Match match; if (count < -1) throw new ArgumentOutOfRangeException("count", SR.GetString(SR.CountTooSmall)); if (startat < 0 || startat > input.Length) throw new ArgumentOutOfRangeException("startat", SR.GetString(SR.BeginIndexNotNegative)); if (count == 0) return input; match = regex.Match(input, startat); if (!match.Success) { return input; } else { StringBuilder sb; if (!regex.RightToLeft) { sb = new StringBuilder(); int prevat = 0; do { if (match.Index != prevat) sb.Append(input, prevat, match.Index - prevat); prevat = match.Index + match.Length; ReplacementImpl(sb, match); if (--count == 0) break; match = match.NextMatch(); } while (match.Success); if (prevat < input.Length) sb.Append(input, prevat, input.Length - prevat); } else { ArrayList al = new ArrayList(); int prevat = input.Length; do { if (match.Index + match.Length != prevat) al.Add(input.Substring(match.Index + match.Length, prevat - match.Index - match.Length)); prevat = match.Index; for (int i = _rules.Count - 1; i >= 0; i--) { int r = (int) _rules[i]; if (r >= 0) al.Add((string) _strings[r]); else al.Add(match.GroupToStringImpl(-Specials - 1 - r)); } if (--count == 0) break; match = match.NextMatch(); } while (match.Success); sb = new StringBuilder(); if (prevat > 0) sb.Append(input, 0, prevat); for (int i = al.Count - 1; i >= 0; i--) { sb.Append((String)al[i]); } } return sb.ToString(); } } /* * Replaces all ocurrances of the regex in the string with the * replacement evaluator. * * Note that the special case of no matches is handled on its own: * with no matches, the input string is returned unchanged. * The right-to-left case is split out because StringBuilder * doesn't handle right-to-left string building directly very well. */ internal static String Replace(MatchEvaluator evaluator, Regex regex, String input, int count, int startat) { Match match; if (evaluator == null) throw new ArgumentNullException("evaluator"); if (count < -1) throw new ArgumentOutOfRangeException("count", SR.GetString(SR.CountTooSmall)); if (startat < 0 || startat > input.Length) throw new ArgumentOutOfRangeException("startat", SR.GetString(SR.BeginIndexNotNegative)); if (count == 0) return input; match = regex.Match(input, startat); if (!match.Success) { return input; } else { StringBuilder sb; if (!regex.RightToLeft) { sb = new StringBuilder(); int prevat = 0; do { if (match.Index != prevat) sb.Append(input, prevat, match.Index - prevat); prevat = match.Index + match.Length; sb.Append(evaluator(match)); if (--count == 0) break; match = match.NextMatch(); } while (match.Success); if (prevat < input.Length) sb.Append(input, prevat, input.Length - prevat); } else { ArrayList al = new ArrayList(); int prevat = input.Length; do { if (match.Index + match.Length != prevat) al.Add(input.Substring(match.Index + match.Length, prevat - match.Index - match.Length)); prevat = match.Index; al.Add(evaluator(match)); if (--count == 0) break; match = match.NextMatch(); } while (match.Success); sb = new StringBuilder(); if (prevat > 0) sb.Append(input, 0, prevat); for (int i = al.Count - 1; i >= 0; i--) { sb.Append((String)al[i]); } } return sb.ToString(); } } /* * Does a split. In the right-to-left case we reorder the * array to be forwards. */ internal static String[] Split(Regex regex, String input, int count, int startat) { Match match; String[] result; if (count < 0) throw new ArgumentOutOfRangeException("count", SR.GetString(SR.CountTooSmall)); if (startat < 0 || startat > input.Length) throw new ArgumentOutOfRangeException("startat", SR.GetString(SR.BeginIndexNotNegative)); if (count == 1) { result = new String[1]; result[0] = input; return result; } count -= 1; match = regex.Match(input, startat); if (!match.Success) { result = new String[1]; result[0] = input; return result; } else { ArrayList al = new ArrayList(); if (!regex.RightToLeft) { int prevat = 0; for (;;) { al.Add(input.Substring(prevat, match.Index - prevat)); prevat = match.Index + match.Length; // add all matched capture groups to the list. for (int i=1; i
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