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|
% generate.ml %
%-----------------------------------------------------------------------------%
begin_section generate;;
% Pretty-printing rules for a subset of ML. %
% These rules are used to generate ML code from a parse-tree. They appear %
% as the ML data structure which represents the rules. No precedence is %
% used to reduce the number of parentheses, because the output is only %
% intended for code generation. %
let PP_to_ML_rules =
% : (print_rule list) %
[
% Rule for use with ML code block rule %
% Prints a node name representing some arbitrary string. %
(`name`,Var_name (`n`,[]),(\x y. true)),[],
(PF_H [Nat 0,PO_leaf (`n`,(\s.s))]);
% Integer constant %
(``,Const_name (`INTCONST`,[Patt_child (Var_name (`n`,[]))]),
(\x y. true)),[],
(PF_H [Nat 0,PO_leaf (`n`,(\s.s))]);
% String constant %
(``,Const_name (`TOKCONST`,[Patt_child (Var_name (`n`,[]))]),
(\x y. true)),[],
(PF_H [Nat 0,PO_constant `\``;
Nat 0,PO_leaf (`n`,(\s.s));
Nat 0,PO_constant `\``
]);
% Variable %
(``,Const_name (`VAR`,[Patt_child (Var_name (`n`,[]))]), (\x y. true)),[],
(PF_H [Nat 0,PO_leaf (`n`,(\s.s))]);
% Concrete type constructor with argument %
(``,Const_name (`CON`,[Patt_child (Var_name (`n`,[]))]), (\x y. true)),[],
(PF_H [Nat 0,PO_leaf (`n`,(\s.s))]);
% Concrete type constructor with no argument %
(``,Const_name (`CON0`,[Patt_child (Var_name (`n`,[]))]), (\x y. true)),[],
(PF_H [Nat 0,PO_leaf (`n`,(\s.s))]);
% Application of unary operator %
(``,Const_name (`UNOP`,[Patt_child (Var_name (`n`,[]));
Patt_child (Var_child `c`)
]), (\x y. true)),[],
(PF_H [Nat 0,PO_constant `(`;
Nat 0,PO_format (PF_HV [(Nat 0,Abs 0,Nat 0),PO_leaf (`n`,(\s.s));
(Nat 0,Abs 0,Nat 0),PO_subcall
((`c`,(\l.l)),[])
]);
Nat 0,PO_constant `)`
]);
% Function application %
(``,Const_name (`APPN`,[Patt_child (Var_child `c1`);
Patt_child (Var_child `c2`)
]), (\x y. true)),[],
(PF_H [Nat 0,PO_constant `(`;
Nat 0,PO_format (PF_HV [(Nat 1,Abs 1,Nat 0),
PO_subcall((`c1`,(\l.l)),[]);
(Nat 1,Abs 1,Nat 0),
PO_subcall((`c2`,(\l.l)),[])
]);
Nat 0,PO_constant `)`
]);
% Abstraction %
(``,Const_name (`ABSTR`,[Patt_child (Var_child `c1`);
Patt_child (Var_child `c2`)
]), (\x y. true)),[],
(PF_H [Nat 0,PO_constant `(\\`;
Nat 0,PO_format
(PF_HV [(Nat 1,Abs 1,Nat 0),
PO_format (PF_H [(Nat 0),
PO_subcall
((`c1`,(\l.l)),[]);
(Nat 0),PO_constant `.`
]);
(Nat 1,Abs 1,Nat 0),PO_subcall((`c2`,(\l.l)),[])
]);
Nat 0,PO_constant `)`
]);
% List of at least one element %
(``,Const_name (`LIST`,[Var_children `cl`;Patt_child (Var_child `c`)]),
(\x y. true)),[],
(PF_H [Nat 0,PO_constant `[`;
Nat 0,PO_format
(PF_HoV
[(Nat 0,Abs 0,Nat 0),
PO_expand
(H_box [Nat 0,PO_subcall ((`cl`,(\l.l)),[]);
Nat 0,PO_constant `;`
]);
(Nat 0,Abs 0,Nat 0),
PO_subcall ((`c`,(\l.l)),[])
]);
Nat 0,PO_constant `]`
]);
% Empty list %
(``,Const_name (`LIST`,[]),(\x y. true)),[],
(PF_H [Nat 0,PO_constant `[]`]);
% Tuple %
(``,Print_loop
(Const_name
(`DUPL`,[Patt_child (Var_child `cl`);
Patt_child (Link_child (((Val (Nat 1)),Default),[]))
]),
Var_child `c`
),(\x y. true)),[],
(PF_H [Nat 0,PO_constant `(`;
Nat 0,PO_format
(PF_HV
[(Nat 0,Abs 0,Nat 0),
PO_expand (H_box [Nat 0,PO_subcall
((`cl`,(\l.l)),[]);
Nat 0,PO_constant `,`
]);
(Nat 0,Abs 0,Nat 0),
PO_subcall ((`c`,(\l.l)),[])
]);
Nat 0,PO_constant `)`
]);
% letrec ... and ... %
(``,Const_name
(`LETREC`,
[Patt_child
(Const_name
(`DUPL`,
[Patt_child (Var_child `var1`);
Patt_child
(Print_loop
(Const_name
(`DUPL`,
[Patt_child (Var_child `varl`);
Patt_child
(Link_child ((Default,Default),[]))
]),
Var_child `varl`
))
]));
Patt_child
(Const_name
(`DUPL`,
[Patt_child (Var_child `body1`);
Patt_child
(Print_loop
(Const_name
(`DUPL`,
[Patt_child (Var_child `bodyl`);
Patt_child
(Link_child ((Default,Default),[]))
]),
Var_child `bodyl`
))
]))
]),(\x y. true)),[],
(PF_V [(Abs 0,Nat 0),
PO_format
(PF_HV [(Nat 1,Inc 1,Nat 0),PO_constant `letrec`;
(Nat 1,Inc 1,Nat 0),
PO_format
(PF_H [Nat 1,PO_subcall ((`var1`,(\l.l)),[]);
Nat 1,PO_constant `=`
]);
(Nat 1,Inc 1,Nat 0),PO_subcall ((`body1`,(\l.l)),[])
]);
(Abs 0,Nat 0),
PO_expand
(HV_box [(Nat 1,Inc 1,Nat 0),PO_constant `and`;
(Nat 1,Inc 1,Nat 0),
PO_expand
(H_box [Nat 1,PO_subcall ((`varl`,(\l.l)),[]);
Nat 1,PO_constant `=`
]);
(Nat 1,Inc 1,Nat 0),PO_subcall ((`bodyl`,(\l.l)),[])
])
]);
% letrec ... %
(``,Const_name (`LETREC`,[Patt_child (Var_child `c1`);
Patt_child (Var_child `c2`)]), (\x y. true)),[],
(PF_HV [(Nat 1,Inc 1,Nat 0),PO_constant `letrec`;
(Nat 1,Inc 1,Nat 0),
PO_format
(PF_H [Nat 1,PO_subcall ((`c1`,(\l.l)),[]);
Nat 1,PO_constant `=`
]);
(Nat 1,Inc 1,Nat 0),PO_subcall ((`c2`,(\l.l)),[])
]);
% Special block of ML code %
(``,Const_name (`ML_FUN`,[Var_children `cl`]), (\x y. true)),[],
(PF_H [Nat 0,PO_constant `(`;
Nat 0,
PO_format
(PF_V [(Abs 0,Nat 0),
PO_context_subcall (`name`,(`cl`,(\l.l)),[])
]);
Nat 0,PO_constant `)`
])
] : print_rule list;;
% Print-rule function for above rules. %
let PP_to_ML_rules_fun =
% : (print_rule_function) %
print_rule_fun PP_to_ML_rules;;
% Write a list of strings to an output port, following all but the last %
% with a line-break. %
let write_strings f port sl =
% : ((string # string -> void) -> string -> string list -> void) %
letrec terminate_strings sl' =
% : (string list -> string list) %
if (null sl')
then []
else if (null (tl sl'))
then [hd sl']
else ((hd sl') ^ `\L`).(terminate_strings (tl sl'))
in do (map (\s. f (port,s)) (terminate_strings sl));;
% Function to generate a list of strings representing ML code from an ML %
% parse-tree for a print-rule. Uses the pretty-printing functions. The %
% function assumes an 80-column output. It indents the text by 4 spaces, %
% and leaves room for a semi-colon at the end of the text. %
% Debugging is active, so that system errors are reported. This is %
% controlled by the first argument to `print_box_to_strings'. %
let generate_rule pt =
% : (print_tree -> string list) %
print_box_to_strings true 4
(print_tree_to_box 78 4 PP_to_ML_rules_fun `` [] pt);;
% Function to print an ML parse-tree for a print-rule. %
let write_rule f port pt =
% : ((string # string -> void) -> string -> print_tree -> void) %
write_strings f port (generate_rule pt);;
% Function to print a list of parse-trees derived from print-rules, %
% terminating all but the last with a semi-colon and a line-break. %
% The last rule is terminated only by a line-break. %
letrec write_rules f port ptl =
% : ((string # string -> void) -> string -> print_tree list -> void) %
if (null ptl)
then failwith `write_rules`
else if (null (tl ptl))
then do (write_rule f port (hd ptl); f (port,`\L`))
else do (write_rule f port (hd ptl);
f (port,`;`);
f (port,`\L`);
write_rules f port (tl ptl));;
% Function to generate a list of strings representing ML code from an ML %
% parse-tree for declarations. Uses the pretty-printing functions. The %
% function assumes an 80-column output. It indents the text by 3 spaces. %
% Debugging is active, so that system errors are reported. This is %
% controlled by the first argument to `print_box_to_strings'. %
let generate_declarations pt =
% : (print_tree -> string list) %
print_box_to_strings true 3
(print_tree_to_box 79 3 PP_to_ML_rules_fun `` [] pt);;
% Function to print an ML parse-tree for declarations. %
let write_declarations f port pt =
% : ((string # string -> void) -> string -> print_tree -> void) %
do (write_strings f port (generate_declarations pt); f (port,`\L`));;
% Generate beginning of ML declaration from name of pretty-printer. %
let generate_head s =
% : (string -> string list) %
[``;
`let `^s^`_rules =`;
``;
` % : (print_rule list) %`;
`\L`
];;
% Write beginning of ML declaration. %
let write_head f port s =
% : ((string # string -> void) -> string -> string -> void) %
write_strings f port (generate_head s);;
% Generate end of ML declaration from name of pretty-printer. %
let generate_tail s =
% : (string -> string list) %
[` ] : print_rule list;;`;
``;
``;
`let `^s^`_rules_fun =`;
``;
` % : (print_rule_function) %`;
``;
` print_rule_fun `^s^`_rules;;`;
`\L`
];;
% Write end of ML declaration. %
let write_tail f port s =
% : ((string # string -> void) -> string -> string -> void) %
write_strings f port (generate_tail s);;
% Write the whole ML translation of a pretty-printer. %
% The parse-tree for the ML translation of the pretty-printer specification %
% is split into name of pretty-printer, declarations (if present), and %
% a list of rules. Each rule is processed seperately so as to avoid giving %
% the pretty-printer too large an amount to process. %
let generate_ML (f:(string # string) -> void) port pt =
% : ((string # string -> void) -> string -> print_tree -> void) %
case pt
of (Print_node (`LET`,[Print_node (`VAR`,[Print_node (s,[])]);
Print_node (`LIST`,ptl)])) .
(do (write_head f port s;
f (port,` [`); f (port,`\L`);
write_rules f port ptl;
write_tail f port s))
| (Print_node (`LET`,[Print_node (`VAR`,[Print_node (s,[])]);
Print_node (`IN`,[pt1; Print_node (`LIST`,ptl)])])) .
(do (write_head f port s;
write_declarations f port pt1;
f (port,` in`); f (port,`\L`);
f (port,` [`); f (port,`\L`);
write_rules f port ptl;
write_tail f port s))
| (_) . failwith `generate_ML`;;
generate_ML;;
end_section generate;;
let generate_ML = it;;
%-----------------------------------------------------------------------------%
|
