monic part 6: the mC programming language and compiler

[F-73P]

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In the previous thread I introduced the mC ("monic C") high-level programming language for the monic calculator. In this thread I'll document the development of a compiler that translates the language into bytecode for execution by a virtual machine.

mC does not conform to any C standard. Features will include:

• recursive functions
• local variables
• multi-dimensional arrays and pointers
  

Below is the EBNF grammar (v1.0) for mC (see the previous thread for information on grammars and EBNF notation):

program \(\rightarrow\) code ENDFILE

code \(\rightarrow\) { var-declaration } { function-declaration } main-function-declaration

var-declaration \(\rightarrow\) ARRAY ID dimensions SEMICOLON | [ "*" ] ID SEMICOLON

dimensions \(\rightarrow\) LEFTBRACKET NUM RIGHTBRACKET { LEFTBRACKET NUM RIGHTBRACKET }

function-declaration \(\rightarrow\) ID [ LEFTPARENTHESIS params RIGHTPARENTHESIS ] LEFTBRACE local-declarations statement-list RIGHTBRACE

main-function-declaration \(\rightarrow\) MAIN LEFTBRACE local-declarations statement-list RIGHTBRACE

params \(\rightarrow\) [ param { COMMA param } ]

param \(\rightarrow\) ID { LEFTBRACKET NUM RIGHTBRACKET } | "*" ID

local-declarations \(\rightarrow\) { LOCAL var-declaration }

statement-list \(\rightarrow\) { statement }

statement \(\rightarrow\) compound-stmt | if-stmt | while-stmt | do-stmt | for-stmt| switch-stmt | return-stmt | read-stmt | write-stmt | assignment-stmt | expression-stmt | goto-stmt | label-stmt | nop-stmt

compound-stmt\(\rightarrow\) LEFTBRACE statement-list RIGHTBRACE

if-stmt \(\rightarrow\) IF LEFTPARENTHESIS Boolean-expression RIGHTPARENTHESIS statement [ ELSE statement ]

while-stmt \(\rightarrow\) WHILE LEFTPARENTHESIS Boolean-expression RIGHTPARENTHESIS statement

do-stmt \(\rightarrow\) DO statement WHILE LEFTPARENTHESIS Boolean-expression RIGHTPARENTHESIS SEMICOLON

for-stmt \(\rightarrow\) FOR LEFTPARENTHESIS [ assignment ] SEMICOLON Boolean-expression SEMICOLON [ addditive-expression ] RIGHTPARENTHESIS statement

switch-stmt \(\rightarrow\) SWITCH LEFTPARENTHESIS var RIGHTPARENTHESIS LEFTBRACE { CASE NUM COLON statement-list BREAK SEMICOLON } [ DEFAULT COLON statement-list ] RIGHTBRACE

var \(\rightarrow\) ID { LEFTBRACKET additive-expression RIGHTBRACKET } | "*" ID

return-stmt \(\rightarrow\) RETURN [ expression ] SEMICOLON

read-stmt \(\rightarrow\) READ var SEMICOLON

write-stmt \(\rightarrow\) WRITE expression SEMICOLON

assignment-stmt \(\rightarrow\) assignment SEMICOLON

expression-stmt \(\rightarrow\) [ expression ] SEMICOLON

goto-stmt \(\rightarrow\) GOTO ID SEMICOLON

label-stmt \(\rightarrow\) ID COLON statement

nop-stmt \(\rightarrow\) NOPR SEMICOLON

assignment \(\rightarrow\) var "=" expression

expression \(\rightarrow\) Boolean-expression | additive-expression

Boolean-expression \(\rightarrow\) logical-expression { boolop logical-expression }

logical-expression \(\rightarrow\) additive-expression relop additive-expression | var | TRUE | FALSE

additive-expression \(\rightarrow\) term { addop term }

term \(\rightarrow\) [ NEGATE ] factor { mulop [ NEGATE ] factor }

factor \(\rightarrow\) LEFTPARENTHESIS additive-expression RIGHTPARENTHESIS | NUM | var | ID LEFTPARENTHESIS args RIGHTPARENTHESIS | var "++" | var "--" | "&" ID { LEFTBRACKET additive-expression RIGHTBRACKET }

args \(\rightarrow\) [ expression { COMMA expression } ]

boolop \(\rightarrow\) "and" | "or" | "not"

relop \(\rightarrow\) "<=" | "<" | ">" | ">=" | "==" | "!="

addop \(\rightarrow\) "+" | "-"

mulop \(\rightarrow\) "*" | "/"