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More work on new arithmetic expressions

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John Whitington 2016-07-19 15:40:00 +01:00
parent 08801a2fd9
commit 718cedd5cf
1 changed files with 80 additions and 3 deletions
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cpdfcommand.ml
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@ -783,6 +783,29 @@ let find_page_crop_miny pdf page = miny (cropbox pdf page)
let find_page_crop_maxx pdf page = maxx (cropbox pdf page)
let find_page_crop_maxy pdf page = maxy (cropbox pdf page)
type expr =
Num of float
| Add of expr * expr
| Mul of expr * expr
| Sub of expr * expr
| Div of expr * expr
type lexeme =
LNum of float | LAdd | LMul | LSub | LDiv | LParen | RParen
let string_of_our_lexeme = function
LNum x -> Printf.sprintf "LNum %f" x;
| LAdd -> Printf.sprintf "LAdd"
| LMul -> Printf.sprintf "LMul"
| LSub -> Printf.sprintf "LSub"
| LDiv -> Printf.sprintf "LDiv"
| LParen -> Printf.sprintf "LParen"
| RParen -> Printf.sprintf "RParen"
let string_of_our_lexemes lexemes =
List.fold_left
(fun x y -> x ^ " " ^ y) "" (List.map string_of_our_lexeme lexemes)
let rec parse_units_again pdf numbers papersize more =
let w, h = points_of_papersize papersize in
parse_units pdf (h::w::numbers) more
@ -884,13 +907,67 @@ and parse_units pdf numbers = function
parse_units pdf numbers more
| Pdfgenlex.LexName "["::more ->
(* The beginning of a mathematical expression for one number *)
let n, rest = parse_expression more in
let n, rest = parse_expression pdf more in
parse_units pdf (n::numbers) rest
| _ -> rev numbers
and really_parse_expression coalesced =
Printf.printf "%s\n" (string_of_our_lexemes coalesced);
Num 4.3
(* Replace +, - by ))+(( etc. Replace * and / by )*( etc. Add (( on left, )) on
right. Now the expression is correctly parenthesised, as if by magic. This is a
trick from a very early FORTRAN compiler. *)
and parenthesise_inner = function
| (LAdd | LSub) as op::t ->
RParen::RParen::op::LParen::LParen::parenthesise_inner t
| (LMul | LDiv) as op::t ->
RParen::op::LParen::parenthesise_inner t
| x::t -> x::parenthesise_inner t
| [] -> []
and parenthesise lexemes =
[LParen; LParen] @ parenthesise_inner lexemes @ [RParen; RParen]
and eval_expr = function
Num x -> x
| _ -> failwith "eval_expr"
and notop = function
"+" | "-" | "*" | "/" | "(" | ")" -> false
| _ -> true
(* We have int/float + an ident [1.6, mm] or [a4portrait] or [PW]. Coalesce those. Now we just have
operators and operands and parentheses. *)
and coalesce_lexemes pdf = function
[] -> []
| Pdfgenlex.LexName "+"::more -> LAdd::coalesce_lexemes pdf more
| Pdfgenlex.LexName "-"::more -> LSub::coalesce_lexemes pdf more
| Pdfgenlex.LexName "/"::more -> LDiv::coalesce_lexemes pdf more
| Pdfgenlex.LexName "*"::more -> LMul::coalesce_lexemes pdf more
| Pdfgenlex.LexName "("::more -> LParen::coalesce_lexemes pdf more
| Pdfgenlex.LexName ")"::more -> RParen::coalesce_lexemes pdf more
| Pdfgenlex.LexInt a::Pdfgenlex.LexName b::more when notop b ->
begin match parse_units pdf [] [Pdfgenlex.LexInt a; Pdfgenlex.LexName b] with
[x] -> LNum x::coalesce_lexemes pdf more
| _ -> failwith "coalesce_lexemes"
end
| Pdfgenlex.LexReal a::Pdfgenlex.LexName b::more when notop b ->
begin match parse_units pdf [] [Pdfgenlex.LexReal a; Pdfgenlex.LexName b] with
[x] -> LNum x::coalesce_lexemes pdf more
| _ -> failwith "coalesce_lexemes"
end
| Pdfgenlex.LexInt a::more -> LNum (float_of_int a)::coalesce_lexemes pdf more
| Pdfgenlex.LexReal a::more -> LNum a::coalesce_lexemes pdf more
| x -> failwith "coalesce_lexemes: unknown lexemes"
(* Parse a mathematical expression such as 1 + 2 * %PW *)
and parse_expression lexemes =
(0.0, [])
and parse_expression pdf lexemes =
let lexemes, rest = cleavewhile (neq (Pdfgenlex.LexName "]")) lexemes in
Printf.printf "%s\n" (Pdfgenlex.string_of_tokens lexemes);
let our_lexemes = coalesce_lexemes pdf lexemes in
let expr = really_parse_expression (parenthesise our_lexemes) in
(eval_expr expr, rest)
let rec space_units_inner = function
| [] -> []