StringThings.pas

{$mode objfpc}{$H+}{$J-}
{$ModeSwitch typehelpers}
unit StringThings;

interface

uses
    sysutils, classes;

type
    TStringListHelper = Class Helper for TStringList
        Public
            Function Reverse : TStringList;
            function FormatAll(fmt_main : String ; fmt_final : String = '') : TStringList;
    end;
    TStringArrayHelper = Type Helper for TStringArray
        Public
            function FormatAll(fmt_main : String ; fmt_final : String = '') : TStringArray;
    end;

function RepeatStr(s: String; c: integer) : String;
function ExtractFileStem(s : String) : String;
procedure TrimAfterSemicolon(var s: String);
function DelimitStr(s : String; delimiter : String; step: Integer = 1) : String;

implementation

// String

// Creates a string where s is repeated c times.
function RepeatStr(s: String; c: integer) : String;
var
    i : Integer;
    l : Integer;
begin
    Result := '';
    if c > 0 then begin
        l := Length(s);
        if l > 0 then begin
            SetLength(Result, l * c);
            for i := 0 to c - 1 do
            begin
                move(s[1], Result[l * i + 1], l);
            end;
        end;
    end;
end;

// Gets the stem of a filename (i.e. without the extension). If it has no
// extension, it just returns the filename.
function ExtractFileStem(s : String) : String;
var
    file_ext : String;
    file_name : String;
begin
    file_ext := ExtractFileExt(s);
    if file_ext = '' then begin
        Result := ExtractFileName(s)
    end else begin
        file_name := ExtractFileName(s);
        Result := copy(file_name, 1, AnsiPos(file_ext, file_name) - 1);
    end;
end;

function DelimitStr(s : String; delimiter : String; step: Integer = 1) : String;
var
    i : Integer;
begin
    Result := '';
    for i := 1 to length(s) do
    begin
        if (i > 1) and ((i - 1) mod step = 0) then begin
            Result += delimiter;
        end;
        Result += copy(s, i, 1);
    end;
end;

// Removes everything in a string after the first semicolon
procedure TrimAfterSemicolon(var s: String);
begin
    if ansipos(';', s) > 0 then s := copy(s, 1, ansipos(';', s));
    s := s.Trim;
end;

// TStringList

// Reverses the order of elements in a TStringList
function TStringListHelper.Reverse() : TStringList;
var
    i : Integer;
begin
    Result := TStringList.Create();
    for i := Self.Count - 1 downto 0 do
    begin
        Result.Add(Self[i]);
    end;
end;

// Takes a TStringArray and formats every element using format_main. If
// fmt_final exists, the last element in the TStringList will be formatted
// with it instead.
// Useful for generating output for a file where the last line needs to be
// different, such as a comma separated list.
function TStringArrayHelper.FormatAll(fmt_main : String ; fmt_final : String = '') : TStringArray;
var
    i : Integer;
begin
    SetLength(Result, length(self));

    // TODO: For both fmt_main and fmt_final, if there is more than one %s, repeat sl[i] in the array

    if AnsiPos('%s', fmt_main) = 0 then
    begin
        WriteLn('FormatStringArray: Missing %s from format_main.');
        halt(-1);
    end;
    if (fmt_final <> '') and (AnsiPos('%s', fmt_main) = 0) then
    begin
        WriteLn('FormatStringArray: Missing %s from fmt_final.');
        halt(-1);
    end;

    for i := 0 to length(self) - 2 do
    begin
        Result[i] := format(fmt_main, [self[i]]);
    end;
    if fmt_final = '' then
        Result[length(Result) - 1] := format(fmt_main, [self[length(self) - 1]])
    else
        Result[length(Result) - 1] := format(fmt_final, [self[length(self) - 1]]);
end;

// Takes a TStringList and formats every element using format_main. If
// fmt_final exists, the last element in the TStringList will be formatted
// with it instead.
// Useful for generating output for a file where the last line needs to be
// different, such as a comma separated list.
function TStringListHelper.FormatAll(fmt_main : String ; fmt_final : String = '') : TStringList;
var
    i : Integer;
begin
    Result := TStringList.Create();

    // TODO: For both fmt_main and fmt_final, if there is more than one %s, repeat sl[i] in the array

    if AnsiPos('%s', fmt_main) = 0 then
    begin
        WriteLn('FormatStringList: Missing %s from format_main.');
        halt(-1);
    end;
    if (fmt_final <> '') and (AnsiPos('%s', fmt_main) = 0) then
    begin
        WriteLn('FormatStringList: Missing %s from fmt_final.');
        halt(-1);
    end;

    for i := 0 to self.Count - 2 do
    begin
        Result.Add(fmt_main, [self[i]]);
    end;
    if fmt_final = '' then
        Result.Add(fmt_main, [self[self.Count - 1]])
    else
        Result.Add(fmt_final, [self[self.Count - 1]]);
end;

end.