[GitHub] [calcite] macroguo-ghy commented on a diff in pull request #3417: [CALCITE-5993] Add CODE_POINTS_TO_STRING, TO_CODE_POINTS function (en…

["macroguo-ghy (via GitHub)" <gi...@apache.org>]

macroguo-ghy commented on code in PR #3417:
URL: https://github.com/apache/calcite/pull/3417#discussion_r1328039931


##########
core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java:
##########
@@ -1130,14 +1130,68 @@ public static String charFromUtf8(int n) {
       assert codePoint instanceof Number;
       long cp = ((Number) codePoint).longValue();
       if (cp < 0 || cp > 255) {
-        throw RESOURCE.inputArgumentsOfCodePointsToBytesOutOfRange(cp).ex();
+        throw RESOURCE.inputArgumentsOfFunctionOutOfRange("CODE_POINTS_TO_BYTES", cp).ex();
       }
       bytes[i] = (byte) cp;
     }
 
     return new ByteString(bytes);
   }
 
+  /**
+   * SQL CODE_POINTS_TO_STRING function.
+   */
+  public static @Nullable String codePointsToString(List codePoints) {
+    StringBuilder sb = new StringBuilder();
+    for (Object codePoint: codePoints) {
+      if (codePoint == null) {
+        return null;
+      }
+      assert codePoint instanceof Number;
+      long cp = ((Number) codePoint).longValue();
+      // Each valid code point should fall within the range of [0, 0xD7FF] and [0xE000, 0x10FFFF]
+      if (cp >= 0 && cp <= 0xD7FF || cp >= 0xE000 && cp <= 0x10FFFF) {
+        sb.append(charFromUtf8((int) cp));
+      } else {
+        throw RESOURCE.inputArgumentsOfFunctionOutOfRange("CODE_POINTS_TO_STRING", cp).ex();
+      }
+    }
+
+    return sb.toString();
+  }
+
+  /**
+   * SQL TO_CODE_POINTS(string) function.
+   */
+  public static @Nullable List<Integer> toCodePoints(String s) {
+    if (s.length() == 0) {
+      return null;
+    }
+    final ImmutableList.Builder<Integer> builder = new ImmutableList.Builder<>();
+    final int length = s.length();
+    int i = 0;
+    while (i < length) {
+      int cp = s.codePointAt(i);
+      builder.add(cp);
+      i += cp == s.charAt(i) ? 1 : 2;
+    }
+    return builder.build();
+  }
+
+  /**
+   * SQL TO_CODE_POINTS(binary) function.

Review Comment:
   I replace it with `SQL TO_CODE_POINTS(string) function for binary string.` 



##########
core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java:
##########
@@ -1793,6 +1793,22 @@ private static RelDataType deriveTypeMapFromEntries(SqlOperatorBinding opBinding
           OperandTypes.ARRAY_OF_INTEGER,
           SqlFunctionCategory.STRING);
 
+  @LibraryOperator(libraries = {BIG_QUERY})

Review Comment:
   Add some comments for three `code_points` functions.



##########
core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java:
##########
@@ -1793,6 +1793,22 @@ private static RelDataType deriveTypeMapFromEntries(SqlOperatorBinding opBinding
           OperandTypes.ARRAY_OF_INTEGER,
           SqlFunctionCategory.STRING);
 
+  @LibraryOperator(libraries = {BIG_QUERY})
+  public static final SqlFunction CODE_POINTS_TO_STRING =
+      SqlBasicFunction.create("CODE_POINTS_TO_STRING",
+          ReturnTypes.VARCHAR_NULLABLE,
+          OperandTypes.ARRAY_OF_INTEGER,
+          SqlFunctionCategory.STRING);
+
+  @LibraryOperator(libraries = {BIG_QUERY})
+  public static final SqlFunction TO_CODE_POINTS =
+      SqlBasicFunction.create("TO_CODE_POINTS",
+          ReturnTypes.INTEGER

Review Comment:
   The order of transform will affect the return types. 
   `INTEGER_NULLABLE.andThen(SqlTypeTransforms.TO_ARRAY)` means: an not null array, which element may be null.
   `INTEGER.andThen(SqlTypeTransforms.TO_ARRAY).andThen(SqlTypeTransforms.TO_NULLABLE)` means: an array may be null, but its element is not null.
   
   In `to_code_points` function, we can not get a result like`[1, NULL, 2, 3]`, the element type of array never be `NULL`, so i use `INTEGER` instead of `INTEGER_NULLABLE`.



##########
core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java:
##########
@@ -1130,14 +1130,68 @@ public static String charFromUtf8(int n) {
       assert codePoint instanceof Number;
       long cp = ((Number) codePoint).longValue();
       if (cp < 0 || cp > 255) {
-        throw RESOURCE.inputArgumentsOfCodePointsToBytesOutOfRange(cp).ex();
+        throw RESOURCE.inputArgumentsOfFunctionOutOfRange("CODE_POINTS_TO_BYTES", cp).ex();

Review Comment:
   I use some keywords like 'out of range' to search whole project, I find only `atanh` function may throw a out of range exception, I replace old code with `inputArgumentsOfFunctionOutOfRange `. And some other "out of range exception" may throw during vaidation phase, I think we don't need to change them.



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