Add a Boolean() builtin to explicitly cast anything to a boolean.

PiperOrigin-RevId: 576240041

documentation/reference/coercions.md

@@ -36,6 +36,7 @@ There are a few ways to coerce a value to a boolean.
 
 *   use it in an [if-expression](control-flow#if)
 *   use it in a [ternary expression](expressions#ternary-operator)
+*   use the built-in function [`Boolean()`](functions#Boolean)
 
 All values have a boolean coercion (sometimes referred to as a 'truthiness'
 check), these mostly follow JavaScript semantics:

documentation/reference/functions.md

@@ -13,6 +13,10 @@ custom external functions, see
 
 ## Basic Functions
 
+### `Boolean(value)` {#Boolean}
+
+Explicitly coerces the argument to a boolean.
+
 ### `checkNotNull(value)` {#checkNotNull}
 
 Throws a runtime exception if the given value is `null` and returns the value

java/src/com/google/template/soy/basicfunctions/BasicFunctions.java

@@ -27,6 +27,7 @@ private BasicFunctions() {}
   public static ImmutableList<SoySourceFunction> functions() {
     return ImmutableList.of(
         // go/keep-sorted start
+        new BooleanFunction(),
         new CeilingFunction(),
         new ConcatListsFunction(),
         new ConcatMapsMethod(),

java/src/com/google/template/soy/basicfunctions/BasicFunctionsRuntime.java

@@ -488,4 +488,8 @@ private static int clampStrIndex(String str, NumberData position) {
   public static boolean isFinite(SoyValue arg) {
     return arg instanceof NumberData && Double.isFinite(arg.numberValue());
   }
+
+  public static boolean booleanFunc(SoyValue value) {
+    return value != null && value.coerceToBoolean();
+  }
 }

java/src/com/google/template/soy/basicfunctions/BooleanFunction.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2009 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.google.template.soy.basicfunctions;
+
+import com.google.template.soy.data.SoyValue;
+import com.google.template.soy.plugin.java.restricted.JavaPluginContext;
+import com.google.template.soy.plugin.java.restricted.JavaValue;
+import com.google.template.soy.plugin.java.restricted.JavaValueFactory;
+import com.google.template.soy.plugin.java.restricted.SoyJavaSourceFunction;
+import com.google.template.soy.plugin.javascript.restricted.JavaScriptPluginContext;
+import com.google.template.soy.plugin.javascript.restricted.JavaScriptValue;
+import com.google.template.soy.plugin.javascript.restricted.JavaScriptValueFactory;
+import com.google.template.soy.plugin.javascript.restricted.SoyJavaScriptSourceFunction;
+import com.google.template.soy.plugin.python.restricted.PythonPluginContext;
+import com.google.template.soy.plugin.python.restricted.PythonValue;
+import com.google.template.soy.plugin.python.restricted.PythonValueFactory;
+import com.google.template.soy.plugin.python.restricted.SoyPythonSourceFunction;
+import com.google.template.soy.shared.restricted.Signature;
+import com.google.template.soy.shared.restricted.SoyFunctionSignature;
+import com.google.template.soy.shared.restricted.SoyPureFunction;
+import java.lang.reflect.Method;
+import java.util.List;
+
+/** Soy function that takes the ceiling of a number. */
+@SoyPureFunction
+@SoyFunctionSignature(
+    name = "Boolean",
+    value =
+        @Signature(
+            parameterTypes = {"?"},
+            returnType = "bool"))
+final class BooleanFunction
+    implements SoyJavaSourceFunction, SoyJavaScriptSourceFunction, SoyPythonSourceFunction {
+
+  @Override
+  public JavaScriptValue applyForJavaScriptSource(
+      JavaScriptValueFactory factory, List<JavaScriptValue> args, JavaScriptPluginContext context) {
+    return factory.global("Boolean").invoke(args.get(0));
+  }
+
+  @Override
+  public PythonValue applyForPythonSource(
+      PythonValueFactory factory, List<PythonValue> args, PythonPluginContext context) {
+    return factory.global("bool").call(args.get(0));
+  }
+
+  // lazy singleton pattern, allows other backends to avoid the work.
+  private static final class Methods {
+    static final Method BOOLEAN_FN =
+        JavaValueFactory.createMethod(BasicFunctionsRuntime.class, "booleanFunc", SoyValue.class);
+  }
+
+  @Override
+  public JavaValue applyForJavaSource(
+      JavaValueFactory factory, List<JavaValue> args, JavaPluginContext context) {
+    return factory.callStaticMethod(Methods.BOOLEAN_FN, args.get(0));
+  }
+}

java/src/com/google/template/soy/jssrc/internal/JavaScriptValueFactoryImpl.java

@@ -272,6 +272,11 @@ public JavaScriptValueImpl invokeMethod(String methodName, JavaScriptValue... ar
           impl.dotAccess(methodName).call(unwrapParams(Arrays.asList(args))));
     }
 
+    @Override
+    public JavaScriptValueImpl invoke(JavaScriptValue... args) {
+      return new JavaScriptValueImpl(impl.call(unwrapParams(Arrays.asList(args))));
+    }
+
     @Override
     public JavaScriptValueImpl accessProperty(String ident) {
       return new JavaScriptValueImpl(impl.dotAccess(ident));
@@ -281,5 +286,6 @@ public JavaScriptValueImpl accessProperty(String ident) {
     public String toString() {
       return impl.getCode(FormatOptions.JSSRC);
     }
+
   }
 }

java/src/com/google/template/soy/plugin/javascript/restricted/JavaScriptValue.java

@@ -48,6 +48,10 @@ default JavaScriptValue invokeMethod(String ident, Iterable<JavaScriptValue> arg
     return invokeMethod(ident, Iterables.toArray(args, JavaScriptValue.class));
   }
 
+  /** Generates a call on the symbol. */
+  JavaScriptValue invoke(JavaScriptValue... args);
+
   /** Accesses a property on the given object. */
   JavaScriptValue accessProperty(String ident);
+
 }