Sunday, November 10, 2013

Recreator – Assignments

Translated assignment statements consists of one (single assignment) or more (list assignment) variables or arrays (references) followed by the expression of the value to assign with an assignment code at the end, which may have the option sub-code indicating the optional LET keyword was entered at the beginning of the statement.  When these statement are being recreated upon reaching the assignment code at the end, the strings of the references will be on the string holding stack (the first or only variable at the bottom) along with the string of the value expression (at the top of the stack).

The new assign recreate function handles the assign double, assign integer, assign double list, assign integer list and assign string list codes.  The assign string code could be at the end of a mixed sub-string assignment statement and these will be handled differently (see July 14).  The strings on the holding stack need to be appended to the output string in reverse order with the necessary separators between them (a comma between the references when there are more than one, and an equal between the last or only reference and the value expression).

To reverse the strings, the assign recreate function contains a local string stack and starts by popping the value expression string from the holding stack and pushing it to this local stack.  A local separator string is set to the assignment operator (an equal) with surrounding spaces.  The routine loops until the holding stack is empty.  For each reference, the separator string is appended and the popped string is pushed to the local stack.  The separator string is set to the comma with a space for the next reference.

A new let recreator support function was also added that checks if the assignment token has the option sub-code set and appends the LET keyword with a space to the output string if it does.  This function will also be used for multiple mixed sub-string assignment statements.  The assign recreate function calls this function and then loops until the local stack is empty appending each string popped to the output string.

A new recreator stack is empty access function was needed to determine if the holding stack is empty.  This was implemented in the recreator class header file since it was only one line of code.  Since the recreator top, top append, and append access functions are also only one line of code, their definitions were also moved to the header file.  Finally, the pointer to the assign recreate function was added to the table entries of the above mentioned assignment codes.

The results for translator tests #1 to #5 (various assignment tests) were changed to the expected results (inputs with spaces added and upper case keywords).  The statements in tests #1 (assignment tests) and #3 (data type assignments) are recreated correctly.  Many of the statements in the other tests are also recreated correctly, but the ones that are not contain string and sub-string list assignments yet to be implemented.

[commit 97c666a9d3]

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