Upstream string_util function.

ios/chrome/common/string_util.mm

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ios/chrome/common/string_util.h"
+
+#import <UIKit/UIKit.h>
+
+#include "base/logging.h"
+#include "base/mac/scoped_block.h"
+#include "base/mac/scoped_nsobject.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/sys_string_conversions.h"
+
+namespace {
+typedef BOOL (^ArrayFilterProcedure)(id object, NSUInteger index, BOOL* stop);
+typedef NSString* (^SubstringExtractionProcedure)(NSUInteger);
+}
+
+NSString* ParseStringWithLink(NSString* text, NSRange* out_link_range) {
+  // Find the range within |text| and create a substring without the link tags.
+  NSRange begin_range = [text rangeOfString:@"BEGIN_LINK[ \t]*"
+                                    options:NSRegularExpressionSearch];
+  NSRange link_text_range = NSMakeRange(NSNotFound, 0);
+  if (begin_range.length == 0) {
+    if (out_link_range)
+      *out_link_range = link_text_range;
+    return text;
+  }
+
+  NSUInteger after_begin_link = NSMaxRange(begin_range);
+  NSRange range_to_search_for_end_link =
+      NSMakeRange(after_begin_link, text.length - after_begin_link);
+  NSRange end_range = [text rangeOfString:@"[ \t]*END_LINK"
+                                  options:NSRegularExpressionSearch
+                                    range:range_to_search_for_end_link];
+  if (end_range.length == 0) {
+    if (out_link_range)
+      *out_link_range = link_text_range;
+    return text;
+  }
+
+  link_text_range.location = after_begin_link;
+  link_text_range.length = end_range.location - link_text_range.location;
+  base::scoped_nsobject<NSMutableString> out_text(
+      [[NSMutableString alloc] init]);
+  // First part - before the link.
+  if (begin_range.location > 0)
+    [out_text appendString:[text substringToIndex:begin_range.location]];
+
+  // Link part.
+  [out_text appendString:[text substringWithRange:link_text_range]];
+
+  // Last part - after the link.
+  NSUInteger after_end_link = NSMaxRange(end_range);
+  if (after_end_link < [text length]) {
+    [out_text appendString:[text substringFromIndex:after_end_link]];
+  }
+
+  link_text_range.location = begin_range.location;
+  if (out_link_range)
+    *out_link_range = link_text_range;
+  return [NSString stringWithString:out_text];
+}
+
+// Ranges of unicode codepage containing drawing characters.
+// 2190—21FF Arrows
+// 2200—22FF Mathematical Operators
+// 2300—23FF Miscellaneous Technical
+// 2400—243F Control Pictures
+// 2440—245F Optical Character Recognition
+// 2460—24FF Enclosed Alphanumerics
+// 2500—257F Box Drawing
+// 2580—259F Block Elements
+// 25A0—25FF Geometric Shapes
+// 2600—26FF Miscellaneous Symbols
+// 2700—27BF Dingbats
+// 27C0—27EF Miscellaneous Mathematical Symbols-A
+// 27F0—27FF Supplemental Arrows-A
+// 2900—297F Supplemental Arrows-B
+// 2980—29FF Miscellaneous Mathematical Symbols-B
+// 2A00—2AFF Supplemental Mathematical Operators
+// 2B00—2BFF Miscellaneous Symbols and Arrows
+// The section 2800—28FF Braille Patterns must be preserved.
+// The list of characters that must be deleted from the selection.
+NSCharacterSet* GraphicCharactersSet() {
+  static NSMutableCharacterSet* graphicalCharsSet;
+  static dispatch_once_t dispatch_once_token;
+  dispatch_once(&dispatch_once_token, ^{
+    graphicalCharsSet = [[NSMutableCharacterSet alloc] init];
+    NSRange graphicalCharsFirstRange = NSMakeRange(0x2190, 0x2800 - 0x2190);
+    NSRange graphicalCharsSecondRange = NSMakeRange(0x2900, 0x2c00 - 0x2900);
+    [graphicalCharsSet addCharactersInRange:graphicalCharsFirstRange];
+    [graphicalCharsSet addCharactersInRange:graphicalCharsSecondRange];
+  });
+  return graphicalCharsSet;
+}
+
+// TODO(marq): Add unit tests for this function.
+NSString* CleanNSStringForDisplay(NSString* dirty,
+                                  BOOL removeGraphicChars,
+                                  BOOL trim) {
+  NSCharacterSet* wspace = [NSCharacterSet whitespaceAndNewlineCharacterSet];
+  NSString* cleanString = dirty;
+  if (removeGraphicChars) {
+    cleanString = [[cleanString
+        componentsSeparatedByCharactersInSet:GraphicCharactersSet()]
+        componentsJoinedByString:@" "];
+  }
+  base::scoped_nsobject<NSMutableArray> spaceSeparatedCompoments(
+      [[cleanString componentsSeparatedByCharactersInSet:wspace] mutableCopy]);
+  ArrayFilterProcedure filter = ^(id object, NSUInteger index, BOOL* stop) {
+    return [object isEqualToString:@""];
+  };
+  [spaceSeparatedCompoments
+      removeObjectsAtIndexes:[spaceSeparatedCompoments
+                                 indexesOfObjectsPassingTest:filter]];
+  cleanString = [spaceSeparatedCompoments componentsJoinedByString:@" "];
+  return trim ? [cleanString stringByTrimmingCharactersInSet:wspace]
+              : cleanString;
+}
+
+std::string CleanStringForDisplay(std::string dirty,
+                                  BOOL removeGraphicChars,
+                                  BOOL trim) {
+  return base::SysNSStringToUTF8(CleanNSStringForDisplay(
+      base::SysUTF8ToNSString(dirty), removeGraphicChars, trim));
+}
+
+// TODO(marq): Add unit tests for this function.
+NSString* SubstringOfWidth(NSString* string,
+                           NSDictionary* attributes,
+                           CGFloat targetWidth,
+                           BOOL trailing) {
+  if (![string length])
+    return nil;
+
+  UIFont* font = [attributes objectForKey:NSFontAttributeName];
+  DCHECK(font);
+
+  // Function to get the correct substring while insulating against
+  // length overrun/underrun.
+  base::mac::ScopedBlock<SubstringExtractionProcedure> getSubstring;
+  if (trailing) {
+    getSubstring.reset([^NSString*(NSUInteger chars) {
+      NSUInteger length = [string length];
+      return [string substringFromIndex:length - MIN(length, chars)];
+    } copy]);
+  } else {
+    getSubstring.reset([^NSString*(NSUInteger chars) {
+      return [string substringToIndex:MIN(chars, [string length])];
+    } copy]);
+  }
+
+  // Guess at the number of characters that will fit, assuming
+  // the font's x-height is about 25% wider than an average character (25%
+  // value was determined experimentally).
+  NSUInteger characters =
+      MIN(targetWidth / (font.xHeight * 0.8), [string length]);
+  NSInteger increment = 1;
+  NSString* substring = getSubstring.get()(characters);
+  CGFloat prevWidth = [substring sizeWithAttributes:attributes].width;
+  do {
+    characters += increment;
+    substring = getSubstring.get()(characters);
+    CGFloat thisWidth = [substring sizeWithAttributes:attributes].width;
+    if (prevWidth > targetWidth) {
+      if (thisWidth < targetWidth)
+        break;  // Shrinking the string, found the right size.
+      else
+        increment = -1;  // Shrink the string
+    } else if (prevWidth < targetWidth) {
+      if (thisWidth < targetWidth)
+        increment = 1;  // Grow the string
+      else {
+        substring = getSubstring.get()(characters - increment);
+        break;  // Growing the string, found the right size.
+      }
+    }
+    prevWidth = thisWidth;
+  } while (characters > 0 && characters < [string length]);
+
+  return substring;
+}