[GitHub] [calcite] danny0405 commented on a change in pull request #1554: [CALCITE-3462] Add method in RelBuilder for conveniently projecting out expressions

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danny0405 commented on a change in pull request #1554: [CALCITE-3462] Add method in RelBuilder for conveniently projecting out expressions
URL: https://github.com/apache/calcite/pull/1554#discussion_r341835919
 
 

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 File path: core/src/main/java/org/apache/calcite/tools/RelBuilder.java
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 @@ -1259,15 +1255,31 @@ public RelBuilder projectPlus(RexNode... nodes) {
     return projectPlus(ImmutableList.copyOf(nodes));
   }
 
-  /** Creates a {@link Project} of all original fields, plus the given list of
+  /** Creates a {@link Project} of all original fields, plus the given
    * expressions. */
   public RelBuilder projectPlus(Iterable<RexNode> nodes) {
     final ImmutableList.Builder<RexNode> builder = ImmutableList.builder();
     return project(builder.addAll(fields()).addAll(nodes).build());
   }
 
-  /** Creates a {@link Project} of the given list
-   * of expressions, using the given names.
+  /** Creates a {@link Project} of all original fields, minus the given
+   * expressions. */
+  public RelBuilder projectMinus(RexNode... expressions) {
+    return projectMinus(ImmutableList.copyOf(expressions));
+  }
+
+  /** Creates a {@link Project} of all original fields, minus the given
+   * expressions. */
+  public RelBuilder projectMinus(Iterable<RexNode> expressions) {
+    List<RexNode> allExpressions = new ArrayList<>(fields());
+    for (RexNode excludeExp : expressions) {
+      allExpressions.remove(excludeExp);
 
 Review comment:
   We may need to throw exception if the specified expression does not exist.

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