From c13781b4a51f0c6d9a92e14efabf9be5bc8b3312 Mon Sep 17 00:00:00 2001
From: Miroslav Pokorny <miroslav.pokorny@gmail.com>
Date: Thu, 7 Dec 2023 07:43:48 +1100
Subject: [PATCH] ExpressionFunctionParameter.setType

---
 .../function/ExpressionFunctionParameter.java | 25 +++++++++++-
 .../ExpressionFunctionParameterTest.java      | 40 +++++++++++++++++++
 2 files changed, 64 insertions(+), 1 deletion(-)

diff --git a/src/main/java/walkingkooka/tree/expression/function/ExpressionFunctionParameter.java b/src/main/java/walkingkooka/tree/expression/function/ExpressionFunctionParameter.java
index 100508f6..36749ee6 100644
--- a/src/main/java/walkingkooka/tree/expression/function/ExpressionFunctionParameter.java
+++ b/src/main/java/walkingkooka/tree/expression/function/ExpressionFunctionParameter.java
@@ -88,7 +88,7 @@ public static <T> ExpressionFunctionParameter<T> with(final ExpressionFunctionPa
                                                           final ExpressionFunctionParameterCardinality cardinality,
                                                           final Set<ExpressionFunctionParameterKind> kinds) {
         Objects.requireNonNull(name, "name");
-        Objects.requireNonNull(type, "type");
+        checkType(type);
         Objects.requireNonNull(typeParameters, "typeParameters");
         Objects.requireNonNull(cardinality, "cardinality");
         Objects.requireNonNull(kinds, "kinds");
@@ -102,6 +102,10 @@ public static <T> ExpressionFunctionParameter<T> with(final ExpressionFunctionPa
         );
     }
 
+    private static <T> Class<T> checkType(final Class<T> type) {
+        return Objects.requireNonNull(type, "type");
+    }
+
     private ExpressionFunctionParameter(final ExpressionFunctionParameterName name,
                                         final Class<T> type,
                                         final ExpressionFunctionParameterCardinality cardinality,
@@ -142,6 +146,25 @@ public Class<T> type() {
         return this.type;
     }
 
+    /**
+     * Would be setter that returns a {@link ExpressionFunctionParameter} with the new type but copying all other properties.
+     * This is particularly useful when updating a {@link ExpressionFunction} parameters such as COUNT which initially has its parameters declared but Object but within a
+     * spreadsheet it needs all parameter values converted to a number.
+     */
+    public <TT> ExpressionFunctionParameter<TT> setType(final Class<TT> type) {
+        checkType(type);
+
+        return this.type.equals(type) ?
+                Cast.to(this) :
+                new ExpressionFunctionParameter<>(
+                        this.name,
+                        type,
+                        this.cardinality,
+                        this.typeParameters,
+                        this.kinds
+                );
+    }
+
     private final Class<T> type;
 
     public List<Class<?>> typeParameters() {
diff --git a/src/test/java/walkingkooka/tree/expression/function/ExpressionFunctionParameterTest.java b/src/test/java/walkingkooka/tree/expression/function/ExpressionFunctionParameterTest.java
index 34aafb5e..c54cbf34 100644
--- a/src/test/java/walkingkooka/tree/expression/function/ExpressionFunctionParameterTest.java
+++ b/src/test/java/walkingkooka/tree/expression/function/ExpressionFunctionParameterTest.java
@@ -167,6 +167,46 @@ public void testSetNameWithDifferent() {
         this.checkKinds(parameter);
     }
 
+    // setType.........................................................................................................
+
+    @Test
+    public void testSetTypeWithNullFails() {
+        assertThrows(
+                NullPointerException.class,
+                () -> this.createObject().setType(null)
+        );
+    }
+
+    @Test
+    public void testSetTypeWithSame() {
+        final ExpressionFunctionParameter<?> parameter = this.createObject();
+        assertSame(
+                parameter,
+                parameter.setType(TYPE)
+        );
+    }
+
+    @Test
+    public void testSetTypeWithDifferent() {
+        final ExpressionFunctionParameter<?> parameter = this.createObject();
+        final Class<ExpressionFunctionParameterTest> type = ExpressionFunctionParameterTest.class;
+
+        final ExpressionFunctionParameter<?> different = parameter.setType(type);
+        assertNotSame(parameter, different);
+
+        this.checkName(different);
+        this.checkType(different, type);
+        this.checkTypeParameters(different);
+        this.checkCardinality(different);
+        this.checkKinds(different);
+
+        this.checkName(parameter);
+        this.checkType(parameter);
+        this.checkTypeParameters(parameter);
+        this.checkCardinality(parameter);
+        this.checkKinds(parameter);
+    }
+
     // setCardinality...................................................................................................
 
     @Test