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mercury/library/string.builder.m
Julien Fischer 94535ec121 Fix spelling and formatting throughout the system.
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util/*.c:
	Fix spelling and doubled-up words.

	Delete trailing whitespace.

	Convert tabs into spaces (where appropriate).
2015-12-02 18:46:14 +11:00

102 lines
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Mathematica

%---------------------------------------------------------------------------%
% vim: ft=mercury ts=4 sw=4 et
%---------------------------------------------------------------------------%
% Copyright (C) 2006-2007 The University of Melbourne.
% This file may only be copied under the terms of the GNU Library General
% Public License - see the file COPYING.LIB in the Mercury distribution.
%---------------------------------------------------------------------------%
%
% File: string.builder.m.
% Main author: maclarty.
%
% This module implements a string builder stream. It can be used to
% build up a string using string or character writers.
%
% To build up a string using this module, you first construct an initial
% string builder state by calling the init function. You can then use
% any instances of stream.writer that write strings or characters to update the
% string builder state, using string.builder.handle as the stream argument.
% Once you've finished writing to the string builder you can get the final
% string by calling string.builder.to_string/1.
%
% For example:
%
% State0 = string.builder.init,
% stream.string_writer.put_int(string.builder.handle, 5, State0, State),
% Str = string.builder.to_string(State), % Str = "5".
%
%---------------------------------------------------------------------------%
:- module string.builder.
:- interface.
:- import_module char.
:- import_module stream.
%---------------------------------------------------------------------------%
:- type handle
---> handle.
:- type state.
:- func init = (string.builder.state::uo) is det.
:- instance stream.stream(string.builder.handle, string.builder.state).
:- instance stream.output(string.builder.handle, string.builder.state).
:- instance stream.writer(string.builder.handle, string, string.builder.state).
:- instance stream.writer(string.builder.handle, char, string.builder.state).
:- func to_string(string.builder.state::di) = (string::uo) is det.
%---------------------------------------------------------------------------%
%---------------------------------------------------------------------------%
:- implementation.
:- import_module list.
:- type state
---> state(list(string)).
init = state([]).
:- instance stream.stream(string.builder.handle, string.builder.state)
where [
name(_, "<<string builder stream>>", !State)
].
:- instance stream.output(string.builder.handle, string.builder.state)
where [
flush(_, !State)
].
:- instance stream.writer(string.builder.handle, string, string.builder.state)
where [
( put(_, String, !State) :-
!.State = state(StringList0),
copy(String, UniqueString),
StringList = [UniqueString | StringList0],
!:State = state(StringList)
)
].
:- instance stream.writer(string.builder.handle, char, string.builder.state)
where [
( put(_, Char, !State) :-
!.State = state(StringList0),
StringList = [string.from_char(Char) | StringList0],
!:State = state(StringList)
)
].
to_string(State) = String :-
State = state(StringList),
String = string.append_list(list.reverse(StringList)).
%---------------------------------------------------------------------------%
:- end_module string.builder.
%---------------------------------------------------------------------------%