| Index: mojo/public/dart/third_party/args/lib/src/usage.dart
|
| diff --git a/mojo/public/dart/third_party/args/lib/src/usage.dart b/mojo/public/dart/third_party/args/lib/src/usage.dart
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| new file mode 100644
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| index 0000000000000000000000000000000000000000..177a810b1efc2af1807a330b3b74eedd30390aa6
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| --- /dev/null
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| +++ b/mojo/public/dart/third_party/args/lib/src/usage.dart
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| @@ -0,0 +1,253 @@
|
| +// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
|
| +// for details. All rights reserved. Use of this source code is governed by a
|
| +// BSD-style license that can be found in the LICENSE file.
|
| +
|
| +library args.src.usage;
|
| +
|
| +import 'dart:math';
|
| +
|
| +import '../args.dart';
|
| +
|
| +/// Takes an [ArgParser] and generates a string of usage (i.e. help) text for
|
| +/// its defined options.
|
| +///
|
| +/// Internally, it works like a tabular printer. The output is divided into
|
| +/// three horizontal columns, like so:
|
| +///
|
| +/// -h, --help Prints the usage information
|
| +/// | | | |
|
| +///
|
| +/// It builds the usage text up one column at a time and handles padding with
|
| +/// spaces and wrapping to the next line to keep the cells correctly lined up.
|
| +class Usage {
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| + static const NUM_COLUMNS = 3; // Abbreviation, long name, help.
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| +
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| + /// A list of the [Option]s intermingled with [String] separators.
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| + final List optionsAndSeparators;
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| +
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| + /// The working buffer for the generated usage text.
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| + StringBuffer buffer;
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| +
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| + /// The column that the "cursor" is currently on.
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| + ///
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| + /// If the next call to [write()] is not for this column, it will correctly
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| + /// handle advancing to the next column (and possibly the next row).
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| + int currentColumn = 0;
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| +
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| + /// The width in characters of each column.
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| + List<int> columnWidths;
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| +
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| + /// The number of sequential lines of text that have been written to the last
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| + /// column (which shows help info).
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| + ///
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| + /// We track this so that help text that spans multiple lines can be padded
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| + /// with a blank line after it for separation. Meanwhile, sequential options
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| + /// with single-line help will be compacted next to each other.
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| + int numHelpLines = 0;
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| +
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| + /// How many newlines need to be rendered before the next bit of text can be
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| + /// written.
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| + ///
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| + /// We do this lazily so that the last bit of usage doesn't have dangling
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| + /// newlines. We only write newlines right *before* we write some real
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| + /// content.
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| + int newlinesNeeded = 0;
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| +
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| + Usage(this.optionsAndSeparators);
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| +
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| + /// Generates a string displaying usage information for the defined options.
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| + /// This is basically the help text shown on the command line.
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| + String generate() {
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| + buffer = new StringBuffer();
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| +
|
| + calculateColumnWidths();
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| +
|
| + for (var optionOrSeparator in optionsAndSeparators) {
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| + if (optionOrSeparator is String) {
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| + // Ensure that there's always a blank line before a separator.
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| + if (buffer.isNotEmpty) buffer.write("\n\n");
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| + buffer.write(optionOrSeparator);
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| + newlinesNeeded = 1;
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| + continue;
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| + }
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| +
|
| + var option = optionOrSeparator as Option;
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| + if (option.hide) continue;
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| +
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| + write(0, getAbbreviation(option));
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| + write(1, getLongOption(option));
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| +
|
| + if (option.help != null) write(2, option.help);
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| +
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| + if (option.allowedHelp != null) {
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| + var allowedNames = option.allowedHelp.keys.toList(growable: false);
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| + allowedNames.sort();
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| + newline();
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| + for (var name in allowedNames) {
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| + write(1, getAllowedTitle(name));
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| + write(2, option.allowedHelp[name]);
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| + }
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| + newline();
|
| + } else if (option.allowed != null) {
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| + write(2, buildAllowedList(option));
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| + } else if (option.defaultValue != null) {
|
| + if (option.isFlag && option.defaultValue == true) {
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| + write(2, '(defaults to on)');
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| + } else if (!option.isFlag) {
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| + write(2, '(defaults to "${option.defaultValue}")');
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| + }
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| + }
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| +
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| + // If any given option displays more than one line of text on the right
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| + // column (i.e. help, default value, allowed options, etc.) then put a
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| + // blank line after it. This gives space where it's useful while still
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| + // keeping simple one-line options clumped together.
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| + if (numHelpLines > 1) newline();
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| + }
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| +
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| + return buffer.toString();
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| + }
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| +
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| + String getAbbreviation(Option option) {
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| + if (option.abbreviation != null) {
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| + return '-${option.abbreviation}, ';
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| + } else {
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| + return '';
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| + }
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| + }
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| +
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| + String getLongOption(Option option) {
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| + var result;
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| + if (option.negatable) {
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| + result = '--[no-]${option.name}';
|
| + } else {
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| + result = '--${option.name}';
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| + }
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| +
|
| + if (option.valueHelp != null) result += "=<${option.valueHelp}>";
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| +
|
| + return result;
|
| + }
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| +
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| + String getAllowedTitle(String allowed) {
|
| + return ' [$allowed]';
|
| + }
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| +
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| + void calculateColumnWidths() {
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| + int abbr = 0;
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| + int title = 0;
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| + for (var option in optionsAndSeparators) {
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| + if (option is! Option) continue;
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| + if (option.hide) continue;
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| +
|
| + // Make room in the first column if there are abbreviations.
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| + abbr = max(abbr, getAbbreviation(option).length);
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| +
|
| + // Make room for the option.
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| + title = max(title, getLongOption(option).length);
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| +
|
| + // Make room for the allowed help.
|
| + if (option.allowedHelp != null) {
|
| + for (var allowed in option.allowedHelp.keys) {
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| + title = max(title, getAllowedTitle(allowed).length);
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| + }
|
| + }
|
| + }
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| +
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| + // Leave a gutter between the columns.
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| + title += 4;
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| + columnWidths = [abbr, title];
|
| + }
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| +
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| + void newline() {
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| + newlinesNeeded++;
|
| + currentColumn = 0;
|
| + numHelpLines = 0;
|
| + }
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| +
|
| + void write(int column, String text) {
|
| + var lines = text.split('\n');
|
| +
|
| + // Strip leading and trailing empty lines.
|
| + while (lines.length > 0 && lines[0].trim() == '') {
|
| + lines.removeRange(0, 1);
|
| + }
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| +
|
| + while (lines.length > 0 && lines[lines.length - 1].trim() == '') {
|
| + lines.removeLast();
|
| + }
|
| +
|
| + for (var line in lines) {
|
| + writeLine(column, line);
|
| + }
|
| + }
|
| +
|
| + void writeLine(int column, String text) {
|
| + // Write any pending newlines.
|
| + while (newlinesNeeded > 0) {
|
| + buffer.write('\n');
|
| + newlinesNeeded--;
|
| + }
|
| +
|
| + // Advance until we are at the right column (which may mean wrapping around
|
| + // to the next line.
|
| + while (currentColumn != column) {
|
| + if (currentColumn < NUM_COLUMNS - 1) {
|
| + buffer.write(padRight('', columnWidths[currentColumn]));
|
| + } else {
|
| + buffer.write('\n');
|
| + }
|
| + currentColumn = (currentColumn + 1) % NUM_COLUMNS;
|
| + }
|
| +
|
| + if (column < columnWidths.length) {
|
| + // Fixed-size column, so pad it.
|
| + buffer.write(padRight(text, columnWidths[column]));
|
| + } else {
|
| + // The last column, so just write it.
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| + buffer.write(text);
|
| + }
|
| +
|
| + // Advance to the next column.
|
| + currentColumn = (currentColumn + 1) % NUM_COLUMNS;
|
| +
|
| + // If we reached the last column, we need to wrap to the next line.
|
| + if (column == NUM_COLUMNS - 1) newlinesNeeded++;
|
| +
|
| + // Keep track of how many consecutive lines we've written in the last
|
| + // column.
|
| + if (column == NUM_COLUMNS - 1) {
|
| + numHelpLines++;
|
| + } else {
|
| + numHelpLines = 0;
|
| + }
|
| + }
|
| +
|
| + String buildAllowedList(Option option) {
|
| + var allowedBuffer = new StringBuffer();
|
| + allowedBuffer.write('[');
|
| + bool first = true;
|
| + for (var allowed in option.allowed) {
|
| + if (!first) allowedBuffer.write(', ');
|
| + allowedBuffer.write(allowed);
|
| + if (allowed == option.defaultValue) {
|
| + allowedBuffer.write(' (default)');
|
| + }
|
| + first = false;
|
| + }
|
| + allowedBuffer.write(']');
|
| + return allowedBuffer.toString();
|
| + }
|
| +}
|
| +
|
| +/// Pads [source] to [length] by adding spaces at the end.
|
| +String padRight(String source, int length) {
|
| + final result = new StringBuffer();
|
| + result.write(source);
|
| +
|
| + while (result.length < length) {
|
| + result.write(' ');
|
| + }
|
| +
|
| + return result.toString();
|
| +}
|
|
|