The XPL Translator Writing System (TWS)

The XPL TWS consists of four programs:
XCOMA compiler for the XPL language written in XPL.
The original XCOM employed a mixed-strategy precedence (MSP) parsing algorithm. Other versions have been modified to use LR(1) or SLR(1) algorithms.
Approximately 4200 source lines.
XPLSMThe interface between XPL programs and the operating system.
XCOM for System/360 was originally written in assembly language. Other ports may use other available languages.
Approximately 1700 source lines.
ANALYZERAn XPL program to parse a BNF grammar definition of a language and generate syntax tables.
Approximately 1500 source lines.
SKELETONA proto-compiler written in XPL. When syntax tables generated by ANALYZER are merged in, SKELETON becomes a syntax checker for the defined language. With the addition of code generator routines, SKELETON becomes a complete compiler for the language.
Approximately 800 source lines.
The BNF grammar for XPL is quite small, consisting of only forty-nine nonterminals.

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