From 8868b5fa2e8b9f40a31035c51519cce40e73f079 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Mon, 2 Nov 2020 13:37:32 -0700
Subject: define compile-time vs runtime behavior

---
 language/statements/index.rst     | 23 +++++++++++++++++++++++
 language/statements/structure.rst | 21 +++++++++++++++++++++
 language/statements/variables.rst | 24 ++++++++++++++++++++++++
 3 files changed, 68 insertions(+)
 create mode 100644 language/statements/index.rst
 create mode 100644 language/statements/structure.rst
 create mode 100644 language/statements/variables.rst

(limited to 'language/statements')

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.
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