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Add line-delimited read presets with --line and --all-lines

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Refer to changes in doc_src/read.txt for more info. Closes #4861.
This commit is contained in:
Mahmoud Al-Qudsi 2018-04-17 06:57:33 -05:00
parent d00474f0fc
commit bd8c8ceb59
3 changed files with 116 additions and 64 deletions
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6
doc_src/read.txt
View file

@ -7,7 +7,7 @@ read [OPTIONS] VARIABLES...
\subsection read-description Description
`read` reads from standard input and either writes the result back to the terminal for use in command substitution or stores the result in one or more shell variables. By default, `read` reads up to the next newline and splits it into the given variables on space, tab and newline. Alternatively, a null character or a maximum number of characters can be used to terminate the input, and other delimiters can be given. Unlike other shells, there is no default variable (such as `REPLY`) for storing the result. Instead, it is printed on stdout.
`read` reads from standard input and either writes the result back to the terminal for use in command substitution or stores the result in one or more shell variables. By default, `read` reads up to the next newline and splits it into given variables on spaces or tabs. Alternatively, a null character or a maximum number of characters can be used to terminate the input, and other delimiters can be given. Unlike other shells, there is no default variable (such as `REPLY`) for storing the result. Instead, it is printed on stdout.
The following options are available:
@ -43,6 +43,10 @@ The following options are available:
- `-z` or `--null` marks the end of the line with the NUL character, instead of newline. This also
disables interactive mode.
- `-L` or `--line` reads a single line at a time from the input stream and stores it in the `N` given variable. No more than `N` lines are consumed (one line per variable) from the input stream.
- `-A` or `--all-lines` splits input into the given variables, separated by line breaks. The entire input stream is consumed and interactive mode is disabled. Probably only useful with `-a` to read all lines into a single array variable. Where possible, ` | while read --line` should be preferred over ` | read --all-lines` as the latter will block until the input stream has been consumed, leading to latency and decreased responsiveness.
`read` reads a single line of input from stdin, breaks it into tokens based on the delimiter set via `-d`/`--delimiter` as a complete string (like `string split` or, if that has not been given the (deprecated) `IFS` shell variable as a set of characters, and then assigns one token to each variable specified in `VARIABLES`. If there are more tokens than variables, the complete remainder is assigned to the last variable. As a special case, if `IFS` is set to the empty string, each character of the input is considered a separate token.
If no parameters are provided, `read` enters a special case that simply provides redirection from `stdin` to `stdout`, useful for command substitution. For instance, the fish shell command below can be used to read data that should be provided via a command line argument from the console instead of hardcoding it in the command itself, allowing the command to both be reused as-is in various contexts with different input values and preventing possibly sensitive text from being included in the shell history:

159
src/builtin_read.cpp
View file

@ -49,27 +49,33 @@ struct read_cmd_opts_t {
bool split_null = false;
bool to_stdout = false;
int nchars = 0;
bool all_lines = false;
bool one_line = false;
};
static const wchar_t *short_options = L":ac:ghilm:n:p:d:suxzP:UR:";
static const struct woption long_options[] = {{L"export", no_argument, NULL, 'x'},
static const wchar_t *short_options = L":Aac:d:ghiLlm:n:p:suxzP:UR:LB";
static const struct woption long_options[] = {
{L"array", no_argument, NULL, 'a'},
{L"all-lines", no_argument, NULL, 'A'},
{L"command", required_argument, NULL, 'c'},
{L"delimiter", required_argument, NULL, 'd'},
{L"export", no_argument, NULL, 'x'},
{L"global", no_argument, NULL, 'g'},
{L"help", no_argument, NULL, 'h'},
{L"line", no_argument, NULL, 'L'},
{L"local", no_argument, NULL, 'l'},
{L"universal", no_argument, NULL, 'U'},
{L"unexport", no_argument, NULL, 'u'},
{L"mode-name", required_argument, NULL, 'm'},
{L"nchars", required_argument, NULL, 'n'},
{L"null", no_argument, NULL, 'z'},
{L"prompt", required_argument, NULL, 'p'},
{L"prompt-str", required_argument, NULL, 'P'},
{L"right-prompt", required_argument, NULL, 'R'},
{L"command", required_argument, NULL, 'c'},
{L"mode-name", required_argument, NULL, 'm'},
{L"silent", no_argument, NULL, 's'},
{L"nchars", required_argument, NULL, 'n'},
{L"delimiter", required_argument, NULL, 'd'},
{L"shell", no_argument, NULL, 'S'},
{L"array", no_argument, NULL, 'a'},
{L"null", no_argument, NULL, 'z'},
{L"help", no_argument, NULL, 'h'},
{NULL, 0, NULL, 0}};
{L"silent", no_argument, NULL, 's'},
{L"unexport", no_argument, NULL, 'u'},
{L"universal", no_argument, NULL, 'U'},
{NULL, 0, NULL, 0}
};
static int parse_cmd_opts(read_cmd_opts_t &opts, int *optind, //!OCLINT(high ncss method)
int argc, wchar_t **argv, parser_t &parser, io_streams_t &streams) {
@ -78,42 +84,44 @@ static int parse_cmd_opts(read_cmd_opts_t &opts, int *optind, //!OCLINT(high nc
wgetopter_t w;
while ((opt = w.wgetopt_long(argc, argv, short_options, long_options, NULL)) != -1) {
switch (opt) {
case L'x': {
opts.place |= ENV_EXPORT;
case 'a': {
opts.array = true;
break;
}
case L'A': {
opts.all_lines = true;
break;
}
case L'c': {
opts.commandline = w.woptarg;
break;
}
case 'd': {
opts.have_delimiter = true;
opts.delimiter = w.woptarg;
break;
}
case 'i': {
streams.err.append_format(_(L"%ls: usage of -i for --silent is deprecated. Please use -s or --silent instead.\n"),
cmd);
return STATUS_INVALID_ARGS;
}
case L'g': {
opts.place |= ENV_GLOBAL;
break;
}
case 'h': {
opts.print_help = true;
break;
}
case L'L': {
opts.one_line = true;
break;
}
case L'l': {
opts.place |= ENV_LOCAL;
break;
}
case L'U': {
opts.place |= ENV_UNIVERSAL;
break;
}
case L'u': {
opts.place |= ENV_UNEXPORT;
break;
}
case L'p': {
opts.prompt = w.woptarg;
break;
}
case L'P': {
opts.prompt_str = w.woptarg;
break;
}
case L'R': {
opts.right_prompt = w.woptarg;
break;
}
case L'c': {
opts.commandline = w.woptarg;
break;
}
case L'm': {
streams.err.append_format(_(L"%ls: flags '--mode-name' / '-m' are now ignored. "
L"Set fish_history instead.\n"),
@ -137,34 +145,40 @@ static int parse_cmd_opts(read_cmd_opts_t &opts, int *optind, //!OCLINT(high nc
}
break;
}
case 'd': {
opts.have_delimiter = true;
opts.delimiter = w.woptarg;
case L'P': {
opts.prompt_str = w.woptarg;
break;
}
case 'i': {
streams.err.append_format(_(L"%ls: usage of -i for --silent is deprecated. Please use -s or --silent instead.\n"),
cmd);
return STATUS_INVALID_ARGS;
case L'p': {
opts.prompt = w.woptarg;
break;
}
case L'R': {
opts.right_prompt = w.woptarg;
break;
}
case 's': {
opts.silent = true;
break;
}
case 'a': {
opts.array = true;
break;
}
case L'S': {
opts.shell = true;
break;
}
case L'z': {
opts.split_null = true;
case L'U': {
opts.place |= ENV_UNIVERSAL;
break;
}
case 'h': {
opts.print_help = true;
case L'u': {
opts.place |= ENV_UNEXPORT;
break;
}
case L'x': {
opts.place |= ENV_EXPORT;
break;
}
case L'z': {
opts.split_null = true;
break;
}
case ':': {
@ -341,11 +355,28 @@ static int read_one_char_at_a_time(int fd, wcstring &buff, int nchars, bool spli
static int validate_read_args(const wchar_t *cmd, read_cmd_opts_t &opts, int argc,
const wchar_t *const *argv, parser_t &parser, io_streams_t &streams) {
if (opts.prompt && opts.prompt_str) {
streams.err.append_format(_(L"%ls: You can't specify both -p and -P\n"), cmd);
streams.err.append_format(_(L"%ls: Options %ls and %ls cannot be used together\n"), cmd, L"-p", L"-P");
builtin_print_help(parser, streams, cmd, streams.err);
return STATUS_INVALID_ARGS;
}
if (opts.have_delimiter && opts.all_lines) {
streams.err.append_format(_(L"%ls: Options %ls and %ls cannot be used together\n"), cmd, L"--delimiter", L"--all-lines");
return STATUS_INVALID_ARGS;
}
if (opts.have_delimiter && opts.one_line) {
streams.err.append_format(_(L"%ls: Options %ls and %ls cannot be used together\n"), cmd, L"--delimiter", L"--line");
return STATUS_INVALID_ARGS;
}
if (opts.one_line && opts.all_lines) {
streams.err.append_format(_(L"%ls: Options %ls and %ls cannot be used together\n"), cmd, L"--all-lines", L"--line");
return STATUS_INVALID_ARGS;
}
if (opts.one_line && opts.split_null) {
streams.err.append_format(_(L"%ls: Options %ls and %ls cannot be used together\n"), cmd, L"-z", L"--line");
return STATUS_INVALID_ARGS;
}
if (opts.prompt_str) {
opts.prompt_cmd = L"echo " + escape_string(opts.prompt_str, ESCAPE_ALL);
opts.prompt = opts.prompt_cmd.c_str();
@ -422,6 +453,21 @@ int builtin_read(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
retval = validate_read_args(cmd, opts, argc, argv, parser, streams);
if (retval != STATUS_CMD_OK) return retval;
if (opts.all_lines) {
// --all-lines is the same as read -d \n -z
opts.have_delimiter = true;
opts.delimiter = L"\n";
opts.split_null = true;
opts.shell = false;
}
else if (opts.one_line) {
// --line is the same as read -d \n
opts.have_delimiter = true;
opts.delimiter = L"\n";
opts.split_null = false;
opts.shell = false;
}
// TODO: Determine if the original set of conditions for interactive reads should be reinstated:
// if (isatty(0) && streams.stdin_fd == STDIN_FILENO && !split_null) {
int stream_stdin_is_a_tty = isatty(streams.stdin_fd);
@ -517,7 +563,8 @@ int builtin_read(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
// We're using a delimiter provided by the user so use the `string split` behavior.
wcstring_list_t splits;
split_about(buff.begin(), buff.end(), opts.delimiter.begin(), opts.delimiter.end(),
&splits, LONG_MAX);
&splits);
env_set(argv[0], opts.place, splits);
}
} else {

3
src/wcstringutil.h
View file

@ -26,9 +26,10 @@ wcstring_range wcstring_tok(wcstring& str, const wcstring& needle,
/// If the iterators are forward, this does the normal thing.
/// If the iterators are backward, this returns reversed strings, in reversed order!
/// If the needle is empty, split on individual elements (characters).
/// Max output entries will be max + 1 (after max splits)
template <typename ITER>
void split_about(ITER haystack_start, ITER haystack_end, ITER needle_start, ITER needle_end,
wcstring_list_t* output, long max, bool no_empty = false) {
wcstring_list_t* output, long max = LONG_MAX, bool no_empty = false) {
long remaining = max;
ITER haystack_cursor = haystack_start;
while (remaining > 0 && haystack_cursor != haystack_end) {