Merge pull request #2762 from ethereum/statemutability-view

Introduce view state-mutability (keep constant as alias)

Changelog.md

@@ -3,6 +3,7 @@
 Features:
  * ABI JSON: Include new field ``statemutability`` with values ``view``, ``nonpayable`` and ``payable``.
  * Parser: Display previous visibility specifier in error if multiple are found.
+ * Parser: Introduce ``view`` keyword on functions (``constant`` remains an alias for ``view``).
  * Syntax Checker: Support ``pragma experimental <feature>;`` to turn on experimental features.
  * Static Analyzer: Warn about large storage structures.
  * Metadata: Store experimental flag in metadata CBOR.

docs/abi-spec.rst

@@ -293,7 +293,7 @@ The JSON format for a contract's interface is given by an array of function and/
   * `name`: the name of the parameter;
   * `type`: the canonical type of the parameter.
 - `outputs`: an array of objects similar to `inputs`, can be omitted if function doesn't return anything;
-- `constant`: `true` if function is :ref:`specified to not modify blockchain state <constant-functions>`);
+- `constant`: `true` if function is :ref:`specified to not modify blockchain state <view-functions>`);
 - `payable`: `true` if function accepts ether, defaults to `false`;
 - `statemutability`: a string with one of the following values: `view` (same as `constant` above), `nonpayable` and `payable` (same as `payable` above).
 

docs/contracts.rst

@@ -461,29 +461,32 @@ value types and strings.
     }
 
 
-.. _constant-functions:
+.. _view-functions:
 
-******************
-Constant Functions
-******************
+**************
+View Functions
+**************
 
-Functions can be declared constant in which case they promise not to modify the state.
+Functions can be declared ``view`` in which case they promise not to modify the state.
 
 ::
 
     pragma solidity ^0.4.0;
 
     contract C {
-        function f(uint a, uint b) constant returns (uint) {
+        function f(uint a, uint b) view returns (uint) {
             return a * (b + 42);
         }
     }
 
 .. note::
-  Getter methods are marked constant.
+  ``constant`` is an alias to ``view``.
+
+.. note::
+  Getter methods are marked ``view``.
 
 .. warning::
-  The compiler does not enforce yet that a constant method is not modifying state.
+  The compiler does not enforce yet that a ``view`` method is not modifying state.
 
 .. index:: ! fallback function, function;fallback
 

docs/grammar.txt

@@ -53,7 +53,7 @@ ArrayTypeName = TypeName '[' Expression? ']'
 FunctionTypeName = 'function' TypeNameList ( 'internal' | 'external' | StateMutability )*
                    ( 'returns' TypeNameList )?
 StorageLocation = 'memory' | 'storage'
-StateMutability = 'constant' | 'payable'
+StateMutability = 'constant' | 'view' | 'payable'
 
 Block = '{' Statement* '}'
 Statement = IfStatement | WhileStatement | ForStatement | Block | InlineAssemblyStatement |

docs/miscellaneous.rst

@@ -505,11 +505,12 @@ Function Visibility Specifiers
 Modifiers
 =========
 
+- ``view`` for functions: Disallow modification of state - this is not enforced yet.
+- ``payable`` for functions: Allows them to receive Ether together with a call.
 - ``constant`` for state variables: Disallows assignment (except initialisation), does not occupy storage slot.
-- ``constant`` for functions: Disallows modification of state - this is not enforced yet.
+- ``constant`` for functions: Same as ``view``.
 - ``anonymous`` for events: Does not store event signature as topic.
 - ``indexed`` for event parameters: Stores the parameter as topic.
-- ``payable`` for functions: Allows them to receive Ether together with a call.
 
 Reserved Keywords
 =================

docs/types.rst

@@ -337,7 +337,7 @@ be passed via and returned from external function calls.
 
 Function types are notated as follows::
 
-    function (<parameter types>) {internal|external} [constant|payable] [returns (<return types>)]
+    function (<parameter types>) {internal|external} [constant|view|payable] [returns (<return types>)]
 
 In contrast to the parameter types, the return types cannot be empty - if the
 function type should not return anything, the whole ``returns (<return types>)``

libsolidity/ast/ASTJsonConverter.cpp

@@ -323,6 +323,7 @@ bool ASTJsonConverter::visit(FunctionDefinition const& _node)
 {
 	std::vector<pair<string, Json::Value>> attributes = {
 		make_pair("name", _node.name()),
+		// FIXME: remove with next breaking release
 		make_pair(m_legacy ? "constant" : "isDeclaredConst", _node.stateMutability() == StateMutability::View),
 		make_pair("payable", _node.isPayable()),
 		make_pair("statemutability", stateMutabilityToString(_node.stateMutability())),
@@ -415,6 +416,7 @@ bool ASTJsonConverter::visit(FunctionTypeName const& _node)
 		make_pair("payable", _node.isPayable()),
 		make_pair("visibility", Declaration::visibilityToString(_node.visibility())),
 		make_pair("statemutability", stateMutabilityToString(_node.stateMutability())),
+		// FIXME: remove with next breaking release
 		make_pair(m_legacy ? "constant" : "isDeclaredConst", _node.stateMutability() == StateMutability::View),
 		make_pair("parameterTypes", toJson(*_node.parameterTypeList())),
 		make_pair("returnParameterTypes", toJson(*_node.returnParameterTypeList())),

libsolidity/ast/Types.h

@@ -993,7 +993,6 @@ public:
 		return *m_declaration;
 	}
 	bool hasDeclaration() const { return !!m_declaration; }
-	bool isConstant() const { return m_stateMutability == StateMutability::View; }
 	/// @returns true if the the result of this function only depends on its arguments
 	/// and it does not modify the state.
 	/// Currently, this will only return true for internal functions like keccak and ecrecover.

libsolidity/interface/ABI.cpp

@@ -35,7 +35,8 @@ Json::Value ABI::generate(ContractDefinition const& _contractDef)
 		Json::Value method;
 		method["type"] = "function";
 		method["name"] = it.second->declaration().name();
-		method["constant"] = it.second->isConstant();
+		// TODO: deprecate constant in a future release
+		method["constant"] = it.second->stateMutability() == StateMutability::View;
 		method["payable"] = it.second->isPayable();
 		method["statemutability"] = stateMutabilityToString(it.second->stateMutability());
 		method["inputs"] = formatTypeList(

libsolidity/parsing/Parser.cpp

@@ -337,7 +337,8 @@ StateMutability Parser::parseStateMutability(Token::Value _token)
 	StateMutability stateMutability(StateMutability::NonPayable);
 	if (_token == Token::Payable)
 		stateMutability = StateMutability::Payable;
-	else if (_token == Token::Constant)
+	// FIXME: constant should be removed at the next breaking release
+	else if (_token == Token::View || _token == Token::Constant)
 		stateMutability = StateMutability::View;
 	else
 		solAssert(false, "Invalid state mutability specifier.");

libsolidity/parsing/Token.h

@@ -176,6 +176,7 @@ namespace solidity
 	K(Throw, "throw", 0)                                               \
 	K(Using, "using", 0)                                               \
 	K(Var, "var", 0)                                                   \
+	K(View, "view", 0)                                                 \
 	K(While, "while", 0)                                               \
 	\
 	/* Ether subdenominations */                                       \
@@ -236,7 +237,6 @@ namespace solidity
 	K(Try, "try", 0)                                                   \
 	K(Type, "type", 0)                                                 \
 	K(TypeOf, "typeof", 0)                                             \
-	K(View, "view", 0)                                                 \
 	/* Illegal token - not able to scan. */                            \
 	T(Illegal, "ILLEGAL", 0)                                           \
 	\
@@ -290,7 +290,7 @@ public:
 	static bool isVisibilitySpecifier(Value op) { return isVariableVisibilitySpecifier(op) || op == External; }
 	static bool isVariableVisibilitySpecifier(Value op) { return op == Public || op == Private || op == Internal; }
 	static bool isLocationSpecifier(Value op) { return op == Memory || op == Storage; }
-	static bool isStateMutabilitySpecifier(Value op) { return op == Constant || op == Payable; }
+	static bool isStateMutabilitySpecifier(Value op) { return op == Constant || op == View || op == Payable; }
 	static bool isEtherSubdenomination(Value op) { return op == SubWei || op == SubSzabo || op == SubFinney || op == SubEther; }
 	static bool isTimeSubdenomination(Value op) { return op == SubSecond || op == SubMinute || op == SubHour || op == SubDay || op == SubWeek || op == SubYear; }
 	static bool isReservedKeyword(Value op) { return (Abstract <= op && op <= TypeOf); }

test/libsolidity/SolidityABIJSON.cpp

@@ -250,7 +250,63 @@ BOOST_AUTO_TEST_CASE(multiple_methods_order)
 	checkInterface(sourceCode, interface);
 }
 
-BOOST_AUTO_TEST_CASE(const_function)
+BOOST_AUTO_TEST_CASE(view_function)
+{
+	char const* sourceCode = R"(
+		contract test {
+			function foo(uint a, uint b) returns(uint d) { return a + b; }
+			function boo(uint32 a) view returns(uint b) { return a * 4; }
+		}
+	)";
+
+	char const* interface = R"([
+	{
+		"name": "foo",
+		"constant": false,
+		"payable" : false,
+		"statemutability": "nonpayable",
+		"type": "function",
+		"inputs": [
+		{
+			"name": "a",
+			"type": "uint256"
+		},
+		{
+			"name": "b",
+			"type": "uint256"
+		}
+		],
+		"outputs": [
+		{
+			"name": "d",
+			"type": "uint256"
+		}
+		]
+	},
+	{
+		"name": "boo",
+		"constant": true,
+		"payable" : false,
+		"statemutability": "view",
+		"type": "function",
+		"inputs": [{
+			"name": "a",
+			"type": "uint32"
+		}],
+		"outputs": [
+		{
+			"name": "b",
+			"type": "uint256"
+		}
+		]
+	}
+	])";
+
+	checkInterface(sourceCode, interface);
+}
+
+// constant is an alias to view above
+BOOST_AUTO_TEST_CASE(constant_function)
 {
 	char const* sourceCode = R"(
 		contract test {

test/libsolidity/SolidityNameAndTypeResolution.cpp

@@ -1172,7 +1172,7 @@ BOOST_AUTO_TEST_CASE(state_variable_accessors)
 	BOOST_REQUIRE(function && function->hasDeclaration());
 	auto returnParams = function->returnParameterTypes();
 	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(false), "uint256");
-	BOOST_CHECK(function->isConstant());
+	BOOST_CHECK(function->stateMutability() == StateMutability::View);
 
 	function = retrieveFunctionBySignature(*contract, "map(uint256)");
 	BOOST_REQUIRE(function && function->hasDeclaration());
@@ -1180,7 +1180,7 @@ BOOST_AUTO_TEST_CASE(state_variable_accessors)
 	BOOST_CHECK_EQUAL(params.at(0)->canonicalName(false), "uint256");
 	returnParams = function->returnParameterTypes();
 	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(false), "bytes4");
-	BOOST_CHECK(function->isConstant());
+	BOOST_CHECK(function->stateMutability() == StateMutability::View);
 
 	function = retrieveFunctionBySignature(*contract, "multiple_map(uint256,uint256)");
 	BOOST_REQUIRE(function && function->hasDeclaration());
@@ -1189,7 +1189,7 @@ BOOST_AUTO_TEST_CASE(state_variable_accessors)
 	BOOST_CHECK_EQUAL(params.at(1)->canonicalName(false), "uint256");
 	returnParams = function->returnParameterTypes();
 	BOOST_CHECK_EQUAL(returnParams.at(0)->canonicalName(false), "bytes4");
-	BOOST_CHECK(function->isConstant());
+	BOOST_CHECK(function->stateMutability() == StateMutability::View);
 }
 
 BOOST_AUTO_TEST_CASE(function_clash_with_state_variable_accessor)

test/libsolidity/SolidityParser.cpp

@@ -918,6 +918,11 @@ BOOST_AUTO_TEST_CASE(multiple_statemutability_specifiers)
 			function f() constant constant {}
 		})";
 	CHECK_PARSE_ERROR(text, "State mutability already specified as \"view\".");
+	text = R"(
+		contract c {
+			function f() constant view {}
+		})";
+	CHECK_PARSE_ERROR(text, "State mutability already specified as \"view\".");
 	text = R"(
 		contract c {
 			function f() payable constant {}