prog: [ vars ] funs;

prog: [ vars ] funs;

vars: 'var' names ';';

vars: 'var' names ';';

names: Name [{ ',' Name }];

names: Name [{ ',' Name }];

funs: { fun };

funs: { fun };

fun: head parms [ block ] ';';

fun: head parms [ block ] ';';

head: 'function' Name;

head: 'function' Name;

parms: '(' [ names ] ')';

parms: '(' [ names ] ')';

block: begin [ vars ] stmts 'end';

block: begin body 'end';

begin: 'begin';

begin: 'begin';

body: [ vars ] [ funs ] stmts;

stmts: stmt [{ ';' stmt }];

stmts: stmt [{ ';' stmt }];

stmt: assign | print | return | block | loop | select;

stmt: assign | print | return | block | loop | select;

assign: symbol action;

assign: symbol action;

action: store | call;

action: store | call;

store: '=' sum;

store: '=' sum;

call: args;

call: args;

args: '(' [ sums ] ')';

args: '(' [ sums ] ')';

print: 'print' sums;

print: 'print' sums;

sums: sum [{ ',' sum }];

sums: sum [{ ',' sum }];

return: 'return' [ sum ];

return: 'return' [ sum ];

loop: While cmp Do [ vars ] stmts 'od';

loop: While cmp Do body 'od';

While: 'while';

While: 'while';

Do: 'do';

Do: 'do';

select: 'if' cmp then [ else ] 'fi';

select: 'if' cmp then [ else ] 'fi';

then: Then [ [ vars ] stmts ];

then: Then [ body ];

else: Else [ vars ] stmts;

else: Else body;

Then: 'then';

Then: 'then';

Else: 'else';

Else: 'else';

cmp: sum rel;

cmp: sum rel;

rel: eq | ne | gt | ge | lt | le;

rel: eq | ne | gt | ge | lt | le;

eq: '=' sum;

eq: '=' sum;

ne: '<>' sum;

ne: '<>' sum;

gt: '>' sum;

gt: '>' sum;

ge: '>=' sum;

ge: '>=' sum;

lt: '<' sum;

lt: '<' sum;

le: '<=' sum;

le: '<=' sum;

sum: product [{ add | subtract }];

sum: product [{ add | subtract }];

add: '+' product;

add: '+' product;

subtract: '-' product;

subtract: '-' product;

product: signed [{ multiply | divide }];

product: signed [{ multiply | divide }];

multiply: '*' signed;

multiply: '*' signed;

divide: '/' signed;

divide: '/' signed;

signed: [ '-' ] term;

signed: [ '-' ] term;

term: input | number | name | '(' sum ')';

term: input | number | name | '(' sum ')';

input: 'input' [ Number ];

input: 'input' [ Number ];

number: Number;

number: Number;

name: symbol [ args ];

name: symbol [ args ];

symbol: Name;

symbol: Name;