diff options
Diffstat (limited to 'language/statements')
-rw-r--r-- | language/statements/index.rst | 23 | ||||
-rw-r--r-- | language/statements/structure.rst | 21 | ||||
-rw-r--r-- | language/statements/variables.rst | 24 |
3 files changed, 68 insertions, 0 deletions
diff --git a/language/statements/index.rst b/language/statements/index.rst new file mode 100644 index 0000000..38bfbb1 --- /dev/null +++ b/language/statements/index.rst @@ -0,0 +1,23 @@ +Statements +---------- + +.. crowbar:element:: Block <- '{' Statement* '}' + + Compile-time Behavior: + + A block is a possibly-empty sequence of statements surrounded by curly braces. + Any declaration or definition within the block must not be visible outside of the block. + + Runtime Behavior: + + When a block is executed, each of the containing statements, in linear order, is executed. + +.. crowbar:element:: Statement <- VariableDefinition / StructureStatement / FlowControlStatement / AssignmentStatement / FragileStatement / ExpressionStatement + + Crowbar has many different types of statement. + +.. toctree:: + :maxdepth: 1 + + variables + structure diff --git a/language/statements/structure.rst b/language/statements/structure.rst new file mode 100644 index 0000000..9330bf6 --- /dev/null +++ b/language/statements/structure.rst @@ -0,0 +1,21 @@ +Structure Statements +^^^^^^^^^^^^^^^^^^^^ + +.. crowbar:element:: StructureStatement <- IfStatement / SwitchStatement / WhileStatement / DoWhileStatement / ForStatement + + A structure statement creates some nonlinear control structure. + There are several types of these structures. + +.. crowbar:element:: IfStatement <- 'if' '(' Expression ')' Block ('else' Block)? + + An if statement allows some action to be performed only sometimes, based on the value of the expression. + + Compile-time Behavior: + + If the expression does not have type bool, the compiler must emit an error. + + Runtime Behavior: + + First, the expression is evaluated. + If the expression evaluates to a ``bool`` value of ``true``, then the first block will be executed. + If the expression evaluates to a ``bool`` value of ``false``, either the second block is executed or nothing is executed. diff --git a/language/statements/variables.rst b/language/statements/variables.rst new file mode 100644 index 0000000..6bc1a6f --- /dev/null +++ b/language/statements/variables.rst @@ -0,0 +1,24 @@ +Variables +^^^^^^^^^ + +.. crowbar:element:: VariableDeclaration <- Type identifier ';' + + Compile-time Behavior: + + A variable declaration specifies the type and name of a variable but not its initial value. + This is only used in :crowbar:ref:`HeaderFile`\ s as part of API boundaries. + + Runtime Behavior: + + A variable declaration has no runtime behavior. + +.. crowbar:element:: VariableDefinition <- Type identifier '=' Expression ';' + + Compile-time Behavior: + + A variable definition specifies the type, name, and initial value of a variable. + If the expression has a type which is not the type specified for the variable, an error must be emitted. + + Runtime Behavior: + + When a variable definition is executed, the expression is evaluated, and its result is made available with the given name. |