Check in the pristine copy of ICU 4.6...

icu46/source/common/unicode/stringpiece.h

+// Copyright (C) 2010, International Business Machines
+// Corporation and others. All Rights Reserved.
+//
+// Copyright 2001 and onwards Google Inc.
+// Author: Sanjay Ghemawat
+
+// This code is a contribution of Google code, and the style used here is
+// a compromise between the original Google code and the ICU coding guidelines.
+// For example, data types are ICU-ified (size_t,int->int32_t),
+// and API comments doxygen-ified, but function names and behavior are
+// as in the original, if possible.
+// Assertion-style error handling, not available in ICU, was changed to
+// parameter "pinning" similar to UnicodeString.
+//
+// In addition, this is only a partial port of the original Google code,
+// limited to what was needed so far. The (nearly) complete original code
+// is in the ICU svn repository at icuhtml/trunk/design/strings/contrib
+// (see ICU ticket 6765, r25517).
+
+#ifndef __STRINGPIECE_H__
+#define __STRINGPIECE_H__
+
+/**
+ * \file 
+ * \brief C++ API: StringPiece: Read-only byte string wrapper class.
+ */
+
+#include "unicode/utypes.h"
+#include "unicode/uobject.h"
+#include "unicode/std_string.h"
+
+// Arghh!  I wish C++ literals were "string".
+
+U_NAMESPACE_BEGIN
+
+/**
+ * A string-like object that points to a sized piece of memory.
+ *
+ * We provide non-explicit singleton constructors so users can pass
+ * in a "const char*" or a "string" wherever a "StringPiece" is
+ * expected.
+ *
+ * Functions or methods may use const StringPiece& parameters to accept either
+ * a "const char*" or a "string" value that will be implicitly converted to
+ * a StringPiece.
+ *
+ * Systematic usage of StringPiece is encouraged as it will reduce unnecessary
+ * conversions from "const char*" to "string" and back again.
+ *
+ * @stable ICU 4.2
+ */
+class U_COMMON_API StringPiece : public UMemory {
+ private:
+  const char*   ptr_;
+  int32_t       length_;
+
+ public:
+  /**
+   * Default constructor, creates an empty StringPiece.
+   * @stable ICU 4.2
+   */
+  StringPiece() : ptr_(NULL), length_(0) { }
+  /**
+   * Constructs from a NUL-terminated const char * pointer.
+   * @param str a NUL-terminated const char * pointer
+   * @stable ICU 4.2
+   */
+  StringPiece(const char* str);
+#if U_HAVE_STD_STRING
+  /**
+   * Constructs from a std::string.
+   * @stable ICU 4.2
+   */
+  StringPiece(const U_STD_NSQ string& str)
+    : ptr_(str.data()), length_(static_cast<int32_t>(str.size())) { }
+#endif
+  /**
+   * Constructs from a const char * pointer and a specified length.
+   * @param offset a const char * pointer (need not be terminated)
+   * @param len the length of the string; must be non-negative
+   * @stable ICU 4.2
+   */
+  StringPiece(const char* offset, int32_t len) : ptr_(offset), length_(len) { }
+  /**
+   * Substring of another StringPiece.
+   * @param x the other StringPiece
+   * @param pos start position in x; must be non-negative and <= x.length().
+   * @stable ICU 4.2
+   */
+  StringPiece(const StringPiece& x, int32_t pos);
+  /**
+   * Substring of another StringPiece.
+   * @param x the other StringPiece
+   * @param pos start position in x; must be non-negative and <= x.length().
+   * @param len length of the substring;
+   *            must be non-negative and will be pinned to at most x.length() - pos.
+   * @stable ICU 4.2
+   */
+  StringPiece(const StringPiece& x, int32_t pos, int32_t len);
+
+  /**
+   * Returns the string pointer. May be NULL if it is empty.
+   *
+   * data() may return a pointer to a buffer with embedded NULs, and the
+   * returned buffer may or may not be null terminated.  Therefore it is
+   * typically a mistake to pass data() to a routine that expects a NUL
+   * terminated string.
+   * @return the string pointer
+   * @stable ICU 4.2
+   */
+  const char* data() const { return ptr_; }
+  /**
+   * Returns the string length. Same as length().
+   * @return the string length
+   * @stable ICU 4.2
+   */
+  int32_t size() const { return length_; }
+  /**
+   * Returns the string length. Same as size().
+   * @return the string length
+   * @stable ICU 4.2
+   */
+  int32_t length() const { return length_; }
+  /**
+   * Returns whether the string is empty.
+   * @return TRUE if the string is empty
+   * @stable ICU 4.2
+   */
+  UBool empty() const { return length_ == 0; }
+
+  /**
+   * Sets to an empty string.
+   * @stable ICU 4.2
+   */
+  void clear() { ptr_ = NULL; length_ = 0; }
+
+  /**
+   * Reset the stringpiece to refer to new data.
+   * @param data pointer the new string data.  Need not be nul terminated.
+   * @param len the length of the new data
+   * @internal
+   */
+  void set(const char* data, int32_t len) { ptr_ = data; length_ = len; }
+
+  /**
+   * Reset the stringpiece to refer to new data.
+   * @param str a pointer to a NUL-terminated string. 
+   * @internal
+   */
+  void set(const char* str);
+
+  /**
+   * Removes the first n string units.
+   * @param n prefix length, must be non-negative and <=length()
+   * @stable ICU 4.2
+   */
+  void remove_prefix(int32_t n) {
+    if (n >= 0) {
+      if (n > length_) {
+        n = length_;
+      }
+      ptr_ += n;
+      length_ -= n;
+    }
+  }
+
+  /**
+   * Removes the last n string units.
+   * @param n suffix length, must be non-negative and <=length()
+   * @stable ICU 4.2
+   */
+  void remove_suffix(int32_t n) {
+    if (n >= 0) {
+      if (n <= length_) {
+        length_ -= n;
+      } else {
+        length_ = 0;
+      }
+    }
+  }
+
+  /**
+   * Maximum integer, used as a default value for substring methods.
+   * @stable ICU 4.2
+   */
+  static const int32_t npos = 0x7fffffff;
+
+  /**
+   * Returns a substring of this StringPiece.
+   * @param pos start position; must be non-negative and <= length().
+   * @param len length of the substring;
+   *            must be non-negative and will be pinned to at most length() - pos.
+   * @return the substring StringPiece
+   * @stable ICU 4.2
+   */
+  StringPiece substr(int32_t pos, int32_t len = npos) const {
+    return StringPiece(*this, pos, len);
+  }
+};
+
+/**
+ * Global operator == for StringPiece
+ * @param x The first StringPiece to compare.
+ * @param y The second StringPiece to compare.
+ * @return TRUE if the string data is equal
+ * @internal
+ */
+U_EXPORT UBool U_EXPORT2 
+operator==(const StringPiece& x, const StringPiece& y);
+
+/**
+ * Global operator != for StringPiece
+ * @param x The first StringPiece to compare.
+ * @param y The second StringPiece to compare.
+ * @return TRUE if the string data is not equal
+ * @internal
+ */
+inline UBool operator!=(const StringPiece& x, const StringPiece& y) {
+  return !(x == y);
+}
+
+U_NAMESPACE_END
+
+#endif  // __STRINGPIECE_H__