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Unified Diff: mojo/public/dart/third_party/args/lib/src/usage.dart

Issue 1346773002: Stop running pub get at gclient sync time and fix build bugs (Closed) Base URL: git@github.com:domokit/mojo.git@master
Patch Set: Created 5 years, 3 months ago
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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
new file mode 100644
index 0000000000000000000000000000000000000000..177a810b1efc2af1807a330b3b74eedd30390aa6
--- /dev/null
+++ b/mojo/public/dart/third_party/args/lib/src/usage.dart
@@ -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 {
+ static const NUM_COLUMNS = 3; // Abbreviation, long name, help.
+
+ /// A list of the [Option]s intermingled with [String] separators.
+ final List optionsAndSeparators;
+
+ /// The working buffer for the generated usage text.
+ StringBuffer buffer;
+
+ /// The column that the "cursor" is currently on.
+ ///
+ /// If the next call to [write()] is not for this column, it will correctly
+ /// handle advancing to the next column (and possibly the next row).
+ int currentColumn = 0;
+
+ /// The width in characters of each column.
+ List<int> columnWidths;
+
+ /// The number of sequential lines of text that have been written to the last
+ /// column (which shows help info).
+ ///
+ /// We track this so that help text that spans multiple lines can be padded
+ /// with a blank line after it for separation. Meanwhile, sequential options
+ /// with single-line help will be compacted next to each other.
+ int numHelpLines = 0;
+
+ /// How many newlines need to be rendered before the next bit of text can be
+ /// written.
+ ///
+ /// We do this lazily so that the last bit of usage doesn't have dangling
+ /// newlines. We only write newlines right *before* we write some real
+ /// content.
+ int newlinesNeeded = 0;
+
+ Usage(this.optionsAndSeparators);
+
+ /// Generates a string displaying usage information for the defined options.
+ /// This is basically the help text shown on the command line.
+ String generate() {
+ buffer = new StringBuffer();
+
+ calculateColumnWidths();
+
+ for (var optionOrSeparator in optionsAndSeparators) {
+ if (optionOrSeparator is String) {
+ // Ensure that there's always a blank line before a separator.
+ if (buffer.isNotEmpty) buffer.write("\n\n");
+ buffer.write(optionOrSeparator);
+ newlinesNeeded = 1;
+ continue;
+ }
+
+ var option = optionOrSeparator as Option;
+ if (option.hide) continue;
+
+ write(0, getAbbreviation(option));
+ write(1, getLongOption(option));
+
+ if (option.help != null) write(2, option.help);
+
+ if (option.allowedHelp != null) {
+ var allowedNames = option.allowedHelp.keys.toList(growable: false);
+ allowedNames.sort();
+ newline();
+ for (var name in allowedNames) {
+ write(1, getAllowedTitle(name));
+ write(2, option.allowedHelp[name]);
+ }
+ newline();
+ } else if (option.allowed != null) {
+ write(2, buildAllowedList(option));
+ } else if (option.defaultValue != null) {
+ if (option.isFlag && option.defaultValue == true) {
+ write(2, '(defaults to on)');
+ } else if (!option.isFlag) {
+ write(2, '(defaults to "${option.defaultValue}")');
+ }
+ }
+
+ // If any given option displays more than one line of text on the right
+ // column (i.e. help, default value, allowed options, etc.) then put a
+ // blank line after it. This gives space where it's useful while still
+ // keeping simple one-line options clumped together.
+ if (numHelpLines > 1) newline();
+ }
+
+ return buffer.toString();
+ }
+
+ String getAbbreviation(Option option) {
+ if (option.abbreviation != null) {
+ return '-${option.abbreviation}, ';
+ } else {
+ return '';
+ }
+ }
+
+ String getLongOption(Option option) {
+ var result;
+ if (option.negatable) {
+ result = '--[no-]${option.name}';
+ } else {
+ result = '--${option.name}';
+ }
+
+ if (option.valueHelp != null) result += "=<${option.valueHelp}>";
+
+ return result;
+ }
+
+ String getAllowedTitle(String allowed) {
+ return ' [$allowed]';
+ }
+
+ void calculateColumnWidths() {
+ int abbr = 0;
+ int title = 0;
+ for (var option in optionsAndSeparators) {
+ if (option is! Option) continue;
+ if (option.hide) continue;
+
+ // Make room in the first column if there are abbreviations.
+ abbr = max(abbr, getAbbreviation(option).length);
+
+ // Make room for the option.
+ title = max(title, getLongOption(option).length);
+
+ // Make room for the allowed help.
+ if (option.allowedHelp != null) {
+ for (var allowed in option.allowedHelp.keys) {
+ title = max(title, getAllowedTitle(allowed).length);
+ }
+ }
+ }
+
+ // Leave a gutter between the columns.
+ title += 4;
+ columnWidths = [abbr, title];
+ }
+
+ void newline() {
+ newlinesNeeded++;
+ currentColumn = 0;
+ numHelpLines = 0;
+ }
+
+ 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);
+ }
+
+ 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.
+ 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();
+}
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