Class ALinearCCompoundExpression

Refers to the operator encountered, if any

Parse the expression.

This method assembles the values represented by each subexpression within its scope and, for each pair of expressions, performs an operation on them. The resulting value is stored as the compound expression's value.

The subexpressions are parsed by constructing an instance of ALinearCExpression and calling its parse method.

This method is not typically called directly; instead, it is called from one of the parseUntil() methods, such as ALinearCCompoundExpression.parseUntilToken. This is because the class represents a collection of expressions which is made up of one or more individual expressions.

Parse a subexpression.

This method is called automatically by ALinearCCompoundExpression.parse. It checks to ensure that the current token represents a valid expression beginning, then creates an instance of ALinearCExpression to parse the expression.

Perform the operation indicated by the ALinearCCompoundExpression.operation. This method is called by ALinearCCompoundExpression.parse after two subexpressions, separated by an operator, have been parsed.

Depending on the value of Self.operation, this method will call Self.performArithmeticOperation, Self.performBitwiseOperation, or Self.performEqualityTestOperation. If the method called returns False, then this method flags a syntax error.

Returns

The total number of errors that occurred while attempting to perform the operation. A value of zero (0) indicates success.

Perform an arithmetic operation that involves Self.value and the value of Self.CurrentElement.

The type of value stored in Self.value determines the type of operation performed:

• If Self.value is a string value, then Self.CurrentElement is cast as a string and then:

  • If Self.operation is lcopPlus, the value of Self.CurrentElement is appended to the end of Self.value.

  • If Self.operation is lcopMinus, then all occurrences of the value specified by Self.CurrentElement are removed from Self.value.

  • If Self.operation is lcopTimes, then the value in Self.value is repeated the number of times specified by Self.CurrentElement.

• If Self.value is a floating-point or integer value, then the value of Self.CurrentElement is cast to the appropriate type and the relevant mathematical operation is performed. For division and modulus division, the method ensures that the value of Self.CurrentElement is not zero (0) so as to avoid division-by-zero errors.

• For all other types, this method fails and returns False.

If an exception is thrown when attempting to cast the value of Self.CurrentElement to the correct type, this method will exit and the caller is expected to handle the exception. When called from ALinearCCompoundExpression.performOperation, a syntax error message is generated in response to the exception.

Returns

True if the operation was successfully performed; False otherwise.

Perform a bitwise or logical operation that involves Self.value and the value of Self.CurrentElement.

The type of value stored in Self.value determines the type of operation performed:

• If Self.value is a boolean value and Self.operation is lcopAnd or lcopOr, then the value of Self.CurrentElement is cast as a boolean value and the relevant logical operation is performed.

• If Self.value is an integer value, Self.CurrentElement is cast to the appropriate type and the relevant bitwise operation is performed.

• For all other types, this method fails and returns False.

If an exception is thrown when attempting to cast the value of Self.CurrentElement to the correct type, this method will exit and the caller is expected to handle the exception. When called from ALinearCCompoundExpression.performOperation, a syntax error message is generated in response to the exception.

Returns

True if the operation was successfully performed; False otherwise.

Perform an equality-test operation that involves Self.value and the value of Self.CurrentElement.

The type of value stored in Self.value determines the type of operation performed:

• If Self.value is a string, then the value of Self.CurrentElement is cast as a string and SysUtils.ansiCompareStr is used to determine the relative equality of the two string values.

• If Self.value is an integer value or a floating point value Self.CurrentElement is cast to the appropriate type and the relevant equality test is performed.

• For all other types, this method fails and returns False.

If an exception is thrown when attempting to cast the value of Self.CurrentElement to the correct type, this method will exit and the caller is expected to handle the exception. When called from ALinearCCompoundExpression.performOperation, a syntax error message is generated in response to the exception.

Returns

True if the operation was successfully performed; False otherwise.

Retrieve a reference to the previous expression parsed by the compound expression.

This method simply casts the return value of Self.PreviousElement as an instance of ALinearCExpression.

Retrieve a reference to the current expression parsed by the compound expression.

This method simply casts the return value of Self.CurrentElement as an instance of ALinearCExpression.

Retrieve the operator encountered while parsing the compound expression, if any.

Although a compound expression will generally consist of two or more subexpressions, separated by an operator, this is not required. It is perfectly valid for a compound expression to consist of a single subexpression with no operators, in which case this method will return zero (0).