Merge pull request #58 from WebAssembly/command-line

Generalize command-line parsing more.

1 files changed, 110 insertions, 38 deletions

diff --git a/src/support/command-line.cpp b/src/support/command-line.cpp
index 3c03d48f4..40e11f60a 100644
--- a/src/support/command-line.cpp
+++ b/src/support/command-line.cpp
@@ -16,50 +16,122 @@
 
 #include "support/command-line.h"
 
-namespace {
-bool optionIs(const char *arg, const char *LongOpt, const char *ShortOpt) {
-  return strcmp(arg, LongOpt) == 0 || strcmp(arg, ShortOpt) == 0;
+using namespace wasm;
+
+Options::Options(const std::string &command, const std::string &description)
+    : debug(false), positional(Arguments::Zero) {
+  add("--help", "-h", "Show this help message and exit", Arguments::Zero,
+      [this, command, description](Options *o, const std::string &) {
+        std::cerr << command;
+        if (positional != Arguments::Zero) std::cerr << ' ' << positionalName;
+        std::cerr << "\n\n" << description << "\n\nOptions:\n";
+        size_t optionWidth = 0;
+        for (const auto &o : options) {
+          optionWidth =
+              std::max(optionWidth, o.longName.size() + o.shortName.size());
+        }
+        // TODO: line-wrap description.
+        for (const auto &o : options) {
+          size_t pad = 1 + optionWidth - o.longName.size() - o.shortName.size();
+          std::cerr << "  " << o.longName << ',' << o.shortName
+                    << std::string(pad, ' ') << o.description << '\n';
+        }
+        std::cerr << '\n';
+        exit(EXIT_SUCCESS);
+      });
+  add("--debug", "-d", "Print debug information to stderr", Arguments::Zero,
+      [](Options *o, const std::string &) { o->debug = true; });
 }
-bool startsWith(const char *str, const char *prefix) {
-  return strncmp(str, prefix, strlen(prefix)) == 0;
+
+Options::~Options() {}
+
+Options &Options::add(const std::string &longName, const std::string &shortName,
+                      const std::string &description, Arguments arguments,
+                      const Action &action) {
+  options.push_back({longName, shortName, description, arguments, action, 0});
+  return *this;
 }
-}  // anonymous namespace
 
-void wasm::processCommandLine(int argc, const char *argv[], Options *options,
-                              const char *help) {
+Options &Options::add_positional(const std::string &name, Arguments arguments,
+                                 const Action &action) {
+  positional = arguments;
+  positionalName = name;
+  positionalAction = action;
+  return *this;
+}
+
+void Options::parse(int argc, const char *argv[]) {
   assert(argc > 0 && "expect at least program name as an argument");
+  size_t positionalsSeen = 0;
+  auto dashes = [](const std::string &s) {
+    for (size_t i = 0;; ++i) {
+      if (s[i] != '-') return i;
+    }
+  };
   for (size_t i = 1, e = argc; i != e; ++i) {
-    if (optionIs(argv[i], "--help", "-h")) {
-      std::cerr << help;
-      exit(EXIT_SUCCESS);
-    } else if (optionIs(argv[i], "--debug", "-d")) {
-      options->debug = true;
-    } else if (optionIs(argv[i], "--output", "-o")) {
-      if (i + 1 == e) {
-        std::cerr << "No output file" << std::endl;
-        exit(EXIT_FAILURE);
-      }
-      if (options->outfile.size()) {
-        std::cerr << "Expected only one output file, got '" << options->outfile
-                  << "' and '" << argv[i] << "'" << std::endl;
-        exit(EXIT_FAILURE);
-      }
-      options->outfile = argv[++i];
-    } else if (startsWith(argv[i], "--")) {
-      size_t j = 2;
-      std::string name;
-      while (argv[i][j] && argv[i][j] != '=') {
-        name += argv[i][j];
-        j++;
-      }
-      options->extra[name] = argv[i][j] == '=' ? &argv[i][j + 1] : "(no value)";
-    } else {
-      if (options->infile.size()) {
-        std::cerr << "Expected only one input file, got '" << options->infile
-                  << "' and '" << argv[i] << "'" << std::endl;
-        exit(EXIT_FAILURE);
+    std::string currentOption = argv[i];
+
+    if (dashes(currentOption) == 0) {
+      // Positional.
+      switch (positional) {
+        case Arguments::Zero:
+          std::cerr << "Unexpected positional argument '" << currentOption
+                    << "'\n";
+          exit(EXIT_FAILURE);
+        case Arguments::One:
+          if (positionalsSeen) {
+            std::cerr << "Unexpected second positional argument '"
+                      << currentOption << "' for " << positionalName << '\n';
+            exit(EXIT_FAILURE);
+          }
+        // Fallthrough.
+        case Arguments::N:
+          positionalAction(this, currentOption);
+          ++positionalsSeen;
       }
-      options->infile = argv[i];
+      continue;
+    }
+
+    // Non-positional.
+    std::string argument;
+    auto equal = currentOption.find_first_of('=');
+    if (equal != std::string::npos) {
+      argument = currentOption.substr(equal + 1);
+      currentOption = currentOption.substr(0, equal - 1);
+    }
+    Option *option = nullptr;
+    for (auto &o : options)
+      if (o.longName == currentOption || o.shortName == currentOption)
+        option = &o;
+    if (!option) {
+      std::cerr << "Unknown option '" << currentOption << "'\n";
+      exit(EXIT_FAILURE);
+    }
+    switch (option->arguments) {
+      case Arguments::Zero:
+        if (argument.size()) {
+          std::cerr << "Unexpected argument '" << argument
+                    << "' for option '" << currentOption << "'\n";
+          exit(EXIT_FAILURE);
+        }
+        break;
+      case Arguments::One:
+        if (option->seen) {
+          std::cerr << "Unexpected second argument '" << argument << "' for '"
+                    << currentOption << "'\n";
+          exit(EXIT_FAILURE);
+        }
+        // Fallthrough.
+      case Arguments::N:
+        if (!argument.size()) {
+          if (i + 1 == e) {
+            std::cerr << "Couldn't find expected argument for '" << currentOption << "'\n";
+            exit(EXIT_FAILURE);
+          }
+          argument = argv[++i];
+        }
     }
+    option->action(this, argument);
+    ++option->seen;
   }
 }