Added Documentation

MathPad/MPExpressionTree.h

@@ -8,13 +8,71 @@
 
 #import "MPExpressionTreeElement.h"
 
+
+
 @class MPExpressionTree;
 
+
+/*!
+    @class      MPExpressionTree
+    @brief      The @c MPExpressionTree class is the main interface for working
+                with the mathematical representation of an expression.
+ 
+    @discussion Expressions are represented as a tree structure of elements (all
+                of which must conform to the @c MPExpressionTreeElement
+                protocol). Most messages sent to instances of the @c
+                MPExpressionTree class are cascaded down different parts of an
+                expression in some way.
+ */
 @interface MPExpressionTree : NSObject <MPExpressionTreeElement>
 
+/*!
+    @property   definedVariable
+    @brief      The variable this expression defines.
+ 
+    @discussion A variable definition must be at the beginning of an expression.
+                If it defines a variable it must start with a single letter
+                followed by an equals sign. The single letter is the name of the
+                variable that is defined.
+ */
 @property (nonatomic, copy) NSString *definedVariable;
+
+
+/*!
+    @property   summands
+    @brief      The summands that make up the receiver.
+ 
+    @discussion A expression mathematically can be interpreted as a series of
+                summands. Summands are the different pars of an expression that
+                are separated by + or - symbols. Every object in the returned
+                array is guaranteed to conform to the @c MPExpressionTreeElement
+                protocol.
+ */
 @property (readonly, nonatomic, strong) NSArray *summands;
 
+
+/*!
+    @method     validateExpectingVariableDefinition:error:
+    @brief      Validates the receiver.
+ 
+    @discussion Using this method you can validate an expression that contains a
+                variable definition. If a variable definition is expected but not
+                found this method returns @c NO. Likewise @c NO is returned if
+                you do not expect a variable definition but one is found.
+ 
+    @param      flag
+                Specifies wether or not to expect a variable definition at the
+                beginning of the expression.
+ 
+    @param      error
+                If there is a syntax error in the receiver this parameter will be
+                set to an appropriate value. If you are not interested in the
+                type of syntax error pass @c NULL.
+ 
+    @return     @c YES if the receiver is valid, @c NO otherwise. If @c NO is
+                returned the @c error parameter should be set to an appropriate
+                value.
+ */
 - (BOOL)validateExpectingVariableDefinition:(BOOL)flag
                                       error:(NSError *__autoreleasing *)error;