add type checks: isString, ...

README.md

@@ -214,6 +214,11 @@ render("{{ exists(\"guests\") }}", data); // "true"
 render("{{ exists(\"city\") }}", data); // "false"
 render("{{ existsIn(time, \"start\") }}", data); // "true"
 render("{{ existsIn(time, neighbour) }}", data); // "false"
+
+// Check if a key is a specific type
+render("{{ isString(neighbour) }}", data); // "true"
+render("{{ isArray(guests) }}", data); // "true"
+// Implemented type checks: isArray, isBoolean, isFloat, isInteger, isNumber, isObject, isString,
 ```
 
 ### Callbacks

src/inja.hpp

@@ -278,6 +278,13 @@ struct Parsed {
 		ReadJson,
 		Exists,
 		ExistsInObject,
+		IsBoolean,
+		IsNumber,
+		IsInteger,
+		IsFloat,
+		IsObject,
+		IsArray,
+		IsString,
 		Default
 	};
 
@@ -521,6 +528,34 @@ public:
 				const json d = eval_expression(element.args[0], data);
 				return d.find(name) != d.end();
 			}
+			case Parsed::Function::IsBoolean: {
+				const json d = eval_expression(element.args[0], data);
+				return d.is_boolean();
+			}
+			case Parsed::Function::IsNumber: {
+				const json d = eval_expression(element.args[0], data);
+				return d.is_number();
+			}
+			case Parsed::Function::IsInteger: {
+				const json d = eval_expression(element.args[0], data);
+				return d.is_number_integer();
+			}
+			case Parsed::Function::IsFloat: {
+				const json d = eval_expression(element.args[0], data);
+				return d.is_number_float();
+			}
+			case Parsed::Function::IsObject: {
+				const json d = eval_expression(element.args[0], data);
+				return d.is_object();
+			}
+			case Parsed::Function::IsArray: {
+				const json d = eval_expression(element.args[0], data);
+				return d.is_array();
+			}
+			case Parsed::Function::IsString: {
+				const json d = eval_expression(element.args[0], data);
+				return d.is_string();
+			}
 		}
 
 		inja_throw("render_error", "unknown function in renderer: " + element.command);
@@ -699,6 +734,13 @@ public:
 		{Parsed::Function::Upper, function_regex("upper", 1)},
 		{Parsed::Function::Exists, function_regex("exists", 1)},
 		{Parsed::Function::ExistsInObject, function_regex("existsIn", 2)},
+		{Parsed::Function::IsBoolean, function_regex("isBoolean", 1)},
+		{Parsed::Function::IsNumber, function_regex("isNumber", 1)},
+		{Parsed::Function::IsInteger, function_regex("isInteger", 1)},
+		{Parsed::Function::IsFloat, function_regex("isFloat", 1)},
+		{Parsed::Function::IsObject, function_regex("isObject", 1)},
+		{Parsed::Function::IsArray, function_regex("isArray", 1)},
+		{Parsed::Function::IsString, function_regex("isString", 1)},
 		{Parsed::Function::ReadJson, Regex{"\\s*([^\\(\\)]*\\S)\\s*"}}
 	};
 

test/src/unit-renderer.cpp

@@ -107,6 +107,10 @@ TEST_CASE("functions") {
 	data["brother"]["name"] = "Chris";
 	data["brother"]["daughters"] = {"Maria", "Helen"};
 	data["property"] = "name";
+	data["age"] = 29;
+	data["is_happy"] = true;
+	data["is_sad"] = false;
+	data["vars"] = {2, 3, 4, 0, -1, -2, -3};
 
 	SECTION("upper") {
 		CHECK( env.render("{{ upper(name) }}", data) == "PETER" );
@@ -222,6 +226,23 @@ TEST_CASE("functions") {
 		CHECK_THROWS_WITH( env.render("{{ existsIn(sister, \"lastname\") }}", data), "[inja.exception.render_error] variable '/sister' not found" );
 		CHECK_THROWS_WITH( env.render("{{ existsIn(brother, sister) }}", data), "[inja.exception.render_error] variable '/sister' not found" );
 	}
+
+	SECTION("isType") {
+		CHECK( env.render("{{ isBoolean(is_happy) }}", data) == "true" );
+		CHECK( env.render("{{ isBoolean(vars) }}", data) == "false" );
+		CHECK( env.render("{{ isNumber(age) }}", data) == "true" );
+		CHECK( env.render("{{ isNumber(name) }}", data) == "false" );
+		CHECK( env.render("{{ isInteger(age) }}", data) == "true" );
+		CHECK( env.render("{{ isInteger(is_happy) }}", data) == "false" );
+		CHECK( env.render("{{ isFloat(temperature) }}", data) == "true" );
+		CHECK( env.render("{{ isFloat(age) }}", data) == "false" );
+		CHECK( env.render("{{ isObject(brother) }}", data) == "true" );
+		CHECK( env.render("{{ isObject(vars) }}", data) == "false" );
+		CHECK( env.render("{{ isArray(vars) }}", data) == "true" );
+		CHECK( env.render("{{ isArray(name) }}", data) == "false" );
+		CHECK( env.render("{{ isString(name) }}", data) == "true" );
+		CHECK( env.render("{{ isString(names) }}", data) == "false" );
+	}
 }
 
 TEST_CASE("callbacks") {