106 lines
3.1 KiB
OCaml
106 lines
3.1 KiB
OCaml
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(* Positions in a file
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A position in a file denotes a single unit belonging to it, for
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example, in an ASCII text file, it is a particular character within
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that file (the unit is the byte in this instance, since in ASCII
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one character is encoded with one byte).
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Units can be either bytes (as ASCII characters) or, more
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generally, unicode points.
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The type for positions is the object type [t].
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We use here lexing positions to denote byte-oriented positions
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(field [byte]), and we manage code points by means of the fields
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[point_num] and [point_bol]. These two fields have a meaning
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similar to the fields [pos_cnum] and [pos_bol], respectively, from
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the standard module [Lexing]. That is to say, [point_num] holds the
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number of code points since the beginning of the file, and
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[point_bol] the number of code points since the beginning of the
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current line.
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The name of the file is given by the field [file], and the line
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number by the field [line].
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*)
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type t = <
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(* Payload *)
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byte : Lexing.position;
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point_num : int;
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point_bol : int;
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file : string;
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line : int;
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(* Setters *)
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set_file : string -> t;
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set_line : int -> t;
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(* The call [pos#new_line s], where the string [s] is either "\n" or
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"\c\r", updates the position [pos] with a new line. *)
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new_line : string -> t;
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add_nl : t;
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(* The call [pos#shift_bytes n] evaluates in a position that is the
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translation of position [pos] of [n] bytes forward in the
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file. The call [pos#shift_one_uchar n] is similar, except that it
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assumes that [n] is the number of bytes making up one unicode
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point. *)
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shift_bytes : int -> t;
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shift_one_uchar : int -> t;
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(* Getters *)
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(* The call [pos#offset `Byte] provides the horizontal offset of the
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position [pos] in bytes. (An offset is the number of units, like
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bytes, since the beginning of the current line.) The call
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[pos#offset `Point] is the offset counted in number of unicode
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points.
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The calls to the method [column] are similar to those to
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[offset], except that they give the curren column number.
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The call [pos#line_offset `Byte] is the offset of the line of
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position [pos], counted in bytes. Dually, [pos#line_offset
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`Point] counts the same offset in code points.
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The call [pos#byte_offset] is the offset of the position [pos]
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since the begininng of the file, counted in bytes.
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*)
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offset : [`Byte | `Point] -> int;
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column : [`Byte | `Point] -> int;
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line_offset : [`Byte | `Point] -> int;
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byte_offset : int;
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(* Predicates *)
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is_ghost : bool;
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(* Conversions to [string] *)
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to_string : ?offsets:bool -> [`Byte | `Point] -> string;
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compact : ?offsets:bool -> [`Byte | `Point] -> string;
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anonymous : ?offsets:bool -> [`Byte | `Point] -> string
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>
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type pos = t
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(* Constructors *)
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val make : byte:Lexing.position -> point_num:int -> point_bol:int -> t
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(* Special positions *)
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val ghost : t (* Same as [Lexing.dummy_pos] *)
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val min : t (* Lexing convention: line 1, offsets to 0 and file to "". *)
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(* Comparisons *)
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val equal : t -> t -> bool
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val lt : t -> t -> bool
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