ICU 56 update step 1

source/common/simplepatternformatter.h

Index: source/common/simplepatternformatter.h
diff --git a/source/common/simplepatternformatter.h b/source/common/simplepatternformatter.h
index b286a79cc35821a254041b75090e1c580245e9c2..6740dc9f47b27c0da747d09762b476ddf011200c 100644
--- a/source/common/simplepatternformatter.h
+++ b/source/common/simplepatternformatter.h
@@ -17,6 +17,8 @@
 
 U_NAMESPACE_BEGIN
 
+class SimplePatternFormatterPlaceholderValues;
+
 struct PlaceholderInfo {
   int32_t id;
   int32_t offset;
@@ -39,7 +41,7 @@ struct PlaceholderInfo {
  * UnicodeString result;
  * UErrorCode status = U_ZERO_ERROR;
  * // Evaluates to: "paul {born} in england"
- * fmt.format("englad", "paul", result, status);
+ * fmt.format("england", "paul", result, status);
  * </pre>
  */
 class U_COMMON_API SimplePatternFormatter : public UMemory {
@@ -91,12 +93,6 @@ public:
     }
 
     /**
-     * Returns true if the pattern this object represents starts with
-     * placeholder id; otherwise, returns false.
-     */
-    UBool startsWithPlaceholder(int32_t id) const;
-
-    /**
      * Returns this pattern with none of the placeholders.
      */
     const UnicodeString &getPatternWithNoPlaceholders() const {
@@ -104,7 +100,7 @@ public:
     }
 
     /**
-     * Formats given value.
+     * Formats given value. arg0 cannot be appendTo.
      */
     UnicodeString &format(
             const UnicodeString &args0,
@@ -112,7 +108,7 @@ public:
             UErrorCode &status) const;
     
     /**
-     * Formats given values.
+     * Formats given values. Neither arg0 nor arg1 can be appendTo.
      */
     UnicodeString &format(
             const UnicodeString &args0,
@@ -121,7 +117,7 @@ public:
             UErrorCode &status) const;
     
     /**
-     * Formats given values.
+     * Formats given values. Neither arg0, arg1, nor arg2 can be appendTo.
      */
     UnicodeString &format(
             const UnicodeString &args0,
@@ -135,37 +131,82 @@ public:
      *
      * The caller retains ownership of all pointers.
      * @param placeholderValues 1st one corresponds to {0}; 2nd to {1};
-     *  3rd to {2} etc.
+     *  3rd to {2} etc. If any of these point to appendTo, this method
+     *  sets status to U_ILLEGAL_ARGUMENT_ERROR.
      * @param placeholderValueCount the number of placeholder values
      *  must be at least large enough to provide values for all placeholders
      *  in this object. Otherwise status set to U_ILLEGAL_ARGUMENT_ERROR.
-     * @param appendTo resulting string appended here. Optimization: If
-     *   the pattern this object represents starts with a placeholder AND
-     *   appendTo references the value of that same placeholder, then that
-     *   placeholder value is not copied to appendTo (Its already there).
-     *   If the value of the starting placeholder is a very large string,
-     *   this optimization can offer huge savings.
+     * @param appendTo resulting string appended here.
      * @param offsetArray The offset of each placeholder value in appendTo
      *  stored here. The first value gets the offset of the value for {0};
      *  the 2nd for {1}; the 3rd for {2} etc. -1 means that the corresponding
      *  placeholder does not exist in this object. If caller is not
      *  interested in offsets, it may pass NULL and 0 for the length.
-     * @param offsetArrayLength the size of offsetArray may be less than
-     *  placeholderValueCount.
+     * @param offsetArrayLength the size of offsetArray. If less than
+     *  placeholderValueCount only the first offsets get recorded. If
+     * greater than placeholderValueCount, then extra values in offset
+     * array are set to -1.
      * @param status any error stored here.
      */
-    UnicodeString &format(
+    UnicodeString &formatAndAppend(
             const UnicodeString * const *placeholderValues,
             int32_t placeholderValueCount,
             UnicodeString &appendTo,
             int32_t *offsetArray,
             int32_t offsetArrayLength,
             UErrorCode &status) const;
+
+    /**
+     * Formats given values.
+     *
+     * The caller retains ownership of all pointers.
+     * @param placeholderValues 1st one corresponds to {0}; 2nd to {1};
+     *  3rd to {2} etc. May include pointer to result in which case
+     *  the previous value of result is used for the corresponding
+     *  placeholder.
+     * @param placeholderValueCount the number of placeholder values
+     *  must be at least large enough to provide values for all placeholders
+     *  in this object. Otherwise status set to U_ILLEGAL_ARGUMENT_ERROR.
+     * @param result resulting string stored here overwriting any previous
+     *   value.
+     * @param offsetArray The offset of each placeholder value in result
+     *  stored here. The first value gets the offset of the value for {0};
+     *  the 2nd for {1}; the 3rd for {2} etc. -1 means that the corresponding
+     *  placeholder does not exist in this object. If caller is not
+     *  interested in offsets, it may pass NULL and 0 for the length.
+     * @param offsetArrayLength the size of offsetArray. If less than
+     *  placeholderValueCount only the first offsets get recorded. If
+     * greater than placeholderValueCount, then extra values in offset
+     * array are set to -1.
+     * @param status any error stored here.
+     */
+    UnicodeString &formatAndReplace(
+            const UnicodeString * const *placeholderValues,
+            int32_t placeholderValueCount,
+            UnicodeString &result,
+            int32_t *offsetArray,
+            int32_t offsetArrayLength,
+            UErrorCode &status) const;
 private:
     UnicodeString noPlaceholders;
     MaybeStackArray<PlaceholderInfo, 3> placeholders;
     int32_t placeholderSize;
     int32_t placeholderCount;
+    UBool firstPlaceholderReused;
+
+    // A Placeholder value that is the same as appendTo is treated as the
+    // empty string.
+    UnicodeString &formatAndAppend(
+            const SimplePatternFormatterPlaceholderValues &placeholderValues,
+            UnicodeString &appendTo,
+            int32_t *offsetArray,
+            int32_t offsetArrayLength) const;
+
+    // Returns the placeholder at the beginning of this pattern
+    // (e.g 3 for placeholder {3}). Returns -1 if the beginning of pattern
+    // is text or if the placeholder at the beginning of this pattern
+    // is used again in the middle of the pattern.
+    int32_t getUniquePlaceholderAtStart() const;
     
     // ensureCapacity ensures that the capacity of the placeholders array
     // is desiredCapacity. If ensureCapacity must resize the placeholders