Factor out and rewrite command-line interface

4 files changed, 563 insertions, 306 deletions

diff --git a/tools/.clang-tidy b/tools/.clang-tidy
index f7c82d78..113631df 100644
--- a/tools/.clang-tidy
+++ b/tools/.clang-tidy
@@ -8,5 +8,4 @@ Checks: >
   -concurrency-mt-unsafe,
   -hicpp-signed-bitwise,
   -llvm-header-guard,
-  -readability-function-cognitive-complexity,
 InheritParentConfig: true
diff --git a/tools/console.c b/tools/console.c
index 94c6dc79..2a861d1b 100644
--- a/tools/console.c
+++ b/tools/console.c
@@ -3,8 +3,15 @@
 
 #include "console.h"
 
-#include "serd/serd.h"
+#include "serd/log.h"
+#include "serd/node.h"
+#include "serd/stream.h"
+#include "serd/string.h"
+#include "serd/syntax.h"
+#include "serd/uri.h"
+#include "serd/version.h"
 #include "zix/allocator.h"
+#include "zix/attributes.h"
 #include "zix/filesystem.h"
 
 #ifdef _WIN32
@@ -15,9 +22,86 @@
 #  include <io.h>
 #endif
 
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
 #include <stdint.h>
+#include <stdlib.h>
 #include <string.h>
 
+#define MAX_DEPTH 128U
+
+ZIX_PURE_FUNC bool
+serd_option_iter_is_end(const OptionIter iter)
+{
+  return iter.a >= iter.argc || iter.argv[iter.a][0] != '-' ||
+         !iter.argv[iter.a][iter.f];
+}
+
+SerdStatus
+serd_option_iter_advance(OptionIter* const iter)
+{
+  if (!iter->argv[iter->a][++iter->f]) {
+    ++iter->a;
+    iter->f = 1;
+  }
+
+  return SERD_SUCCESS;
+}
+
+SerdStatus
+serd_tool_setup(SerdTool* const   tool,
+                const char* const program,
+                SerdCommonOptions options)
+{
+  // Open the output first, since if that fails we have nothing to do
+  const char* const out_path = options.out_filename;
+  if (!((tool->out = serd_open_tool_output(out_path)).stream)) {
+    fprintf(stderr,
+            "%s: failed to open output file (%s)\n",
+            program,
+            strerror(errno));
+    return SERD_BAD_STREAM;
+  }
+
+  // We have something to write to, so build the writing environment
+  const SerdLimits limits = {options.stack_size, MAX_DEPTH};
+  if (!(tool->world = serd_world_new(NULL)) ||
+      serd_world_set_limits(tool->world, limits) ||
+      !(tool->env = serd_create_env(
+          NULL, program, options.base_uri, options.out_filename)) ||
+      !(tool->writer = serd_writer_new(
+          tool->world,
+          serd_choose_syntax(
+            tool->world, options.output, options.out_filename, SERD_NQUADS),
+          options.output.flags,
+          tool->env,
+          &tool->out,
+          options.block_size))) {
+    fprintf(stderr, "%s: failed to set up writing environment\n", program);
+    return SERD_UNKNOWN_ERROR;
+  }
+
+  return SERD_SUCCESS;
+}
+
+SerdStatus
+serd_tool_cleanup(SerdTool tool)
+{
+  SerdStatus st = SERD_SUCCESS;
+  if (tool.out.stream) {
+    // Close the output stream explicitly to check if there were any errors
+    if ((st = serd_close_output(&tool.out))) {
+      perror("write error");
+    }
+  }
+
+  serd_writer_free(tool.writer);
+  serd_env_free(tool.env);
+  serd_world_free(tool.world);
+  return st;
+}
+
 void
 serd_set_stream_utf8_mode(FILE* const stream)
 {
@@ -28,7 +112,7 @@ serd_set_stream_utf8_mode(FILE* const stream)
 #endif
 }
 
-int
+SerdStatus
 serd_print_version(const char* const program)
 {
   printf("%s %d.%d.%d <http://drobilla.net/software/serd>\n",
@@ -42,34 +126,90 @@ serd_print_version(const char* const program)
          "This is free software; you are free to change and redistribute it.\n"
          "There is NO WARRANTY, to the extent permitted by law.\n");
 
-  return 0;
+  return SERD_FAILURE;
+}
+
+SerdStatus
+serd_get_argument(OptionIter* const iter, const char** const argument)
+{
+  const char flag = iter->argv[iter->a][iter->f++];
+
+  if (iter->argv[iter->a][iter->f] || (iter->a + 1) == iter->argc) {
+    fprintf(
+      stderr, "%s: option requires an argument -- %c\n", iter->argv[0], flag);
+    return SERD_BAD_ARG;
+  }
+
+  *argument = iter->argv[++iter->a];
+  ++iter->a;
+  iter->f = 1;
+  return SERD_SUCCESS;
+}
+
+SerdStatus
+serd_get_size_argument(OptionIter* const iter, size_t* const argument)
+{
+  SerdStatus  st     = SERD_SUCCESS;
+  const char* string = NULL;
+  if ((st = serd_get_argument(iter, &string))) {
+    return st;
+  }
+
+  char*      endptr = NULL;
+  const long size   = strtol(string, &endptr, 10);
+  if (size <= 0 || size == LONG_MAX || *endptr != '\0') {
+    return SERD_BAD_ARG;
+  }
+
+  *argument = (size_t)size;
+  return SERD_SUCCESS;
 }
 
 SerdStatus
 serd_set_base_uri_from_path(SerdEnv* const env, const char* const path)
 {
-  char* const input_path = zix_canonical_path(NULL, path);
-  if (!input_path) {
+  const size_t path_len  = strlen(path);
+  char* const  real_path = zix_canonical_path(NULL, path);
+  if (!real_path) {
     return SERD_BAD_ARG;
   }
 
-  SerdNode* const file_uri = serd_node_new(
-    NULL, serd_a_file_uri(serd_string(input_path), serd_empty_string()));
+  const size_t real_path_len = strlen(real_path);
+  SerdNode*    base_node     = NULL;
+  if (path[path_len - 1] == '/' || path[path_len - 1] == '\\') {
+    char* const base_path = (char*)calloc(real_path_len + 2, 1);
+
+    memcpy(base_path, real_path, real_path_len + 1);
+    base_path[real_path_len] = path[path_len - 1];
 
-  serd_env_set_base_uri(env, serd_node_string_view(file_uri));
-  serd_node_free(NULL, file_uri);
-  zix_free(NULL, input_path);
+    base_node = serd_node_new(
+      NULL, serd_a_file_uri(serd_string(base_path), serd_empty_string()));
+
+    free(base_path);
+  } else {
+    base_node = serd_node_new(
+      NULL, serd_a_file_uri(serd_string(real_path), serd_empty_string()));
+  }
+
+  serd_env_set_base_uri(env, serd_node_string_view(base_node));
+  serd_node_free(NULL, base_node);
+  zix_free(NULL, real_path);
 
   return SERD_SUCCESS;
 }
 
 SerdSyntax
-serd_choose_syntax(SerdWorld* const  world,
-                   const SerdSyntax  requested,
-                   const char* const filename)
+serd_choose_syntax(SerdWorld* const        world,
+                   const SerdSyntaxOptions options,
+                   const char* const       filename,
+                   const SerdSyntax        fallback)
 {
-  if (requested) {
-    return requested;
+  if (options.overridden || options.syntax != SERD_SYNTAX_EMPTY) {
+    return options.syntax;
+  }
+
+  if (!filename || !strcmp(filename, "-")) {
+    return fallback;
   }
 
   const SerdSyntax guessed = serd_guess_syntax(filename);
@@ -118,7 +258,26 @@ serd_set_input_option(const SerdStringView   name,
     }
   }
 
-  return SERD_FAILURE;
+  return SERD_BAD_ARG;
+}
+
+SerdStatus
+serd_parse_input_argument(OptionIter* const        iter,
+                          SerdSyntaxOptions* const options)
+{
+  SerdStatus  st       = SERD_SUCCESS;
+  const char* argument = NULL;
+
+  if (!(st = serd_get_argument(iter, &argument))) {
+    if ((st = serd_set_input_option(
+           serd_string(argument), &options->syntax, &options->flags))) {
+      fprintf(stderr, "%s: unknown option \"%s\"\n", iter->argv[0], argument);
+    } else if (!strcmp(argument, "empty") || options->syntax) {
+      options->overridden = true;
+    }
+  }
+
+  return st;
 }
 
 SerdStatus
@@ -154,9 +313,87 @@ serd_set_output_option(const SerdStringView   name,
     }
   }
 
+  return SERD_BAD_ARG;
+}
+
+SerdStatus
+serd_parse_output_argument(OptionIter* const        iter,
+                           SerdSyntaxOptions* const options)
+{
+  SerdStatus  st       = SERD_SUCCESS;
+  const char* argument = NULL;
+
+  if (!(st = serd_get_argument(iter, &argument))) {
+    if ((st = serd_set_output_option(
+           serd_string(argument), &options->syntax, &options->flags))) {
+      fprintf(stderr, "%s: unknown option \"%s\"\n", iter->argv[0], argument);
+    } else if (!strcmp(argument, "empty") || options->syntax) {
+      options->overridden = true;
+    }
+  }
+
+  return st;
+}
+
+SerdStatus
+serd_parse_common_option(OptionIter* const iter, SerdCommonOptions* const opts)
+{
+  const char opt = iter->argv[iter->a][iter->f];
+  switch (opt) {
+  case 'B':
+    return serd_get_argument(iter, &opts->base_uri);
+
+  case 'I':
+    return serd_parse_input_argument(iter, &opts->input);
+
+  case 'O':
+    return serd_parse_output_argument(iter, &opts->output);
+
+  case 'b':
+    return serd_get_size_argument(iter, &opts->block_size);
+
+  case 'k':
+    return serd_get_size_argument(iter, &opts->stack_size);
+
+  case 'o':
+    return serd_get_argument(iter, &opts->out_filename);
+
+  default:
+    break;
+  }
+
   return SERD_FAILURE;
 }
 
+SerdEnv*
+serd_create_env(SerdAllocator* const allocator,
+                const char* const    program,
+                const char* const    base_string,
+                const char* const    out_filename)
+{
+  const bool is_rebase = base_string && !strcmp(base_string, "rebase");
+  if (is_rebase && !out_filename) {
+    fprintf(stderr, "%s: rebase requires an output filename\n", program);
+    return NULL;
+  }
+
+  if (base_string && serd_uri_string_has_scheme(base_string)) {
+    return serd_env_new(allocator, serd_string(base_string));
+  }
+
+  SerdEnv* const env = serd_env_new(allocator, serd_empty_string());
+  if (base_string && base_string[0]) {
+    const SerdStatus st = serd_set_base_uri_from_path(env, base_string);
+    if (st) {
+      fprintf(stderr, "%s: invalid base URI \"%s\"\n", program, base_string);
+      serd_env_free(env);
+      return NULL;
+    }
+  }
+
+  return env;
+}
+
 /// Wrapper for getc that is compatible with SerdReadFunc but faster than fread
 static size_t
 serd_file_read_byte(void* buf, size_t size, size_t nmemb, void* stream)
@@ -201,3 +438,65 @@ serd_open_tool_output(const char* const filename)
 
   return serd_open_output_file(filename);
 }
+
+SerdStatus
+serd_read_source(SerdWorld* const        world,
+                 const SerdCommonOptions opts,
+                 SerdEnv* const          env,
+                 const SerdSyntax        syntax,
+                 SerdInputStream* const  in,
+                 const char* const       name,
+                 const SerdSink* const   sink)
+{
+  SerdReader* const reader =
+    serd_reader_new(world, syntax, opts.input.flags, env, sink);
+
+  SerdNode* const name_node = serd_node_new(NULL, serd_a_string(name));
+  SerdStatus st = serd_reader_start(reader, in, name_node, opts.block_size);
+  serd_node_free(NULL, name_node);
+  if (!st) {
+    st = serd_reader_read_document(reader);
+  }
+
+  serd_reader_free(reader);
+  return st;
+}
+
+SerdStatus
+serd_read_inputs(SerdWorld* const        world,
+                 const SerdCommonOptions opts,
+                 SerdEnv* const          env,
+                 const intptr_t          n_inputs,
+                 char* const* const      inputs,
+                 const SerdSink* const   sink)
+{
+  SerdStatus st = SERD_SUCCESS;
+
+  for (intptr_t i = 0; !st && i < n_inputs; ++i) {
+    // Use the filename as the base URI if possible if user didn't override it
+    const char* const in_path = inputs[i];
+    if (!opts.base_uri[0] && !!strcmp(in_path, "-")) {
+      serd_set_base_uri_from_path(env, in_path);
+    }
+
+    // Open the input stream
+    SerdInputStream in = serd_open_tool_input(in_path);
+    if (!in.stream) {
+      return SERD_BAD_ARG;
+    }
+
+    // Read the entire file
+    st = serd_read_source(
+      world,
+      opts,
+      env,
+      serd_choose_syntax(world, opts.input, in_path, SERD_TRIG),
+      &in,
+      !strcmp(in_path, "-") ? "stdin" : in_path,
+      sink);
+
+    serd_close_input(&in);
+  }
+
+  return st;
+}
diff --git a/tools/console.h b/tools/console.h
index a7e8423f..d475aebc 100644
--- a/tools/console.h
+++ b/tools/console.h
@@ -6,29 +6,85 @@
 
 #include "serd/env.h"
 #include "serd/input_stream.h"
+#include "serd/memory.h"
 #include "serd/output_stream.h"
 #include "serd/reader.h"
+#include "serd/sink.h"
 #include "serd/status.h"
 #include "serd/string_view.h"
 #include "serd/syntax.h"
 #include "serd/world.h"
 #include "serd/writer.h"
 
+#include <stdbool.h>
+#include <stdint.h>
 #include <stdio.h>
 
+// Iterator over command-line options with support for BSD-style flag merging
+typedef struct {
+  char* const* argv; ///< Complete argument vector (from main)
+  int          argc; ///< Total number of arguments (from main)
+  int          a;    ///< Argument index (index into argv)
+  int          f;    ///< Flag index (offset in argv[arg])
+} OptionIter;
+
+// Options for the input or output syntax
+typedef struct {
+  SerdSyntax syntax;     ///< User-specified syntax, or empty
+  uint32_t   flags;      ///< SerdReaderFlags or SerdWriterFlags
+  bool       overridden; ///< True if syntax was explicitly given
+} SerdSyntaxOptions;
+
+// Options common to all command-line tools
+typedef struct {
+  const char*       base_uri;
+  const char*       out_filename;
+  size_t            block_size;
+  size_t            stack_size;
+  SerdSyntaxOptions input;
+  SerdSyntaxOptions output;
+} SerdCommonOptions;
+
+// Common "global" state of a command-line tool that writes data
+typedef struct {
+  SerdOutputStream out;
+  SerdWorld*       world;
+  SerdEnv*         env;
+  SerdWriter*      writer;
+} SerdTool;
+
+bool
+serd_option_iter_is_end(OptionIter iter);
+
+SerdStatus
+serd_option_iter_advance(OptionIter* iter);
+
+SerdStatus
+serd_tool_setup(SerdTool* tool, const char* program, SerdCommonOptions options);
+
+SerdStatus
+serd_tool_cleanup(SerdTool tool);
+
 void
 serd_set_stream_utf8_mode(FILE* stream);
 
-int
+SerdStatus
 serd_print_version(const char* program);
 
 SerdStatus
 serd_set_base_uri_from_path(SerdEnv* env, const char* path);
 
 SerdSyntax
-serd_choose_syntax(SerdWorld*  world,
-                   SerdSyntax  requested,
-                   const char* filename);
+serd_choose_syntax(SerdWorld*        world,
+                   SerdSyntaxOptions options,
+                   const char*       filename,
+                   SerdSyntax        fallback);
+
+SerdStatus
+serd_get_argument(OptionIter* iter, const char** argument);
+
+SerdStatus
+serd_get_size_argument(OptionIter* iter, size_t* argument);
 
 SerdStatus
 serd_set_input_option(SerdStringView   name,
@@ -36,14 +92,46 @@ serd_set_input_option(SerdStringView   name,
                       SerdReaderFlags* flags);
 
 SerdStatus
+serd_parse_input_argument(OptionIter* iter, SerdSyntaxOptions* options);
+
+SerdStatus
 serd_set_output_option(SerdStringView   name,
                        SerdSyntax*      syntax,
                        SerdWriterFlags* flags);
 
+SerdStatus
+serd_parse_output_argument(OptionIter* iter, SerdSyntaxOptions* options);
+
+SerdStatus
+serd_parse_common_option(OptionIter* iter, SerdCommonOptions* opts);
+
+SerdEnv*
+serd_create_env(SerdAllocator* allocator,
+                const char*    program,
+                const char*    base_string,
+                const char*    out_filename);
+
 SerdInputStream
 serd_open_tool_input(const char* filename);
 
 SerdOutputStream
 serd_open_tool_output(const char* filename);
 
+SerdStatus
+serd_read_source(SerdWorld*        world,
+                 SerdCommonOptions opts,
+                 SerdEnv*          env,
+                 SerdSyntax        syntax,
+                 SerdInputStream*  in,
+                 const char*       name,
+                 const SerdSink*   sink);
+
+SerdStatus
+serd_read_inputs(SerdWorld*        world,
+                 SerdCommonOptions opts,
+                 SerdEnv*          env,
+                 intptr_t          n_inputs,
+                 char* const*      inputs,
+                 const SerdSink*   sink);
+
 #endif // SERD_TOOLS_CONSOLE_H
diff --git a/tools/serd-pipe.c b/tools/serd-pipe.c
index 66600006..bbed9fa8 100644
--- a/tools/serd-pipe.c
+++ b/tools/serd-pipe.c
@@ -4,344 +4,215 @@
 #include "console.h"
 
 #include "serd/canon.h"
-#include "serd/env.h"
 #include "serd/input_stream.h"
 #include "serd/log.h"
-#include "serd/node.h"
-#include "serd/output_stream.h"
 #include "serd/reader.h"
 #include "serd/sink.h"
 #include "serd/status.h"
 #include "serd/string_view.h"
 #include "serd/syntax.h"
-#include "serd/world.h"
 #include "serd/writer.h"
-#include "zix/allocator.h"
-#include "zix/filesystem.h"
 
-#include <errno.h>
-#include <limits.h>
 #include <stdbool.h>
+#include <stdint.h>
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
 
-#define SERDI_ERROR(msg) fprintf(stderr, "serd-pipe: " msg)
-#define SERDI_ERRORF(fmt, ...) fprintf(stderr, "serd-pipe: " fmt, __VA_ARGS__)
+/* Application (after parsing command-line arguments) */
 
-#define MAX_DEPTH 128U
-
-static int
-print_usage(const char* const name, const bool error)
-{
-  static const char* const description =
-    "Read and write RDF syntax.\n"
-    "Use - for INPUT to read from standard input.\n\n"
-    "  -B BASE_URI  Base URI.\n"
-    "  -C           Convert literals to canonical form.\n"
-    "  -I SYNTAX    Input syntax (turtle/ntriples/trig/nquads),\n"
-    "               or flag (lax/variables/verbatim).\n"
-    "  -O SYNTAX    Output syntax (empty/turtle/ntriples/nquads),\n"
-    "               or flag (ascii/expanded/verbatim/terse/lax).\n"
-    "  -b BYTES     I/O block size.\n"
-    "  -h           Display this help and exit.\n"
-    "  -k BYTES     Parser stack size.\n"
-    "  -q           Suppress all output except data.\n"
-    "  -r ROOT_URI  Keep relative URIs within ROOT_URI.\n"
-    "  -s STRING    Parse STRING as input.\n"
-    "  -v           Display version information and exit.\n"
-    "  -w FILENAME  Write output to FILENAME instead of stdout.\n";
-
-  FILE* const os = error ? stderr : stdout;
-  fprintf(os, "%s", error ? "\n" : "");
-  fprintf(os, "Usage: %s [OPTION]... INPUT...\n", name);
-  fprintf(os, "%s", description);
-  return error ? 1 : 0;
-}
-
-static int
-missing_arg(const char* const name, const char opt)
-{
-  SERDI_ERRORF("option requires an argument -- '%c'\n", opt);
-  return print_usage(name, true);
-}
+// All options
+typedef struct {
+  SerdCommonOptions common;
+  const char*       root_uri;
+  const char*       input_string;
+  char* const*      inputs;
+  intptr_t          n_inputs;
+  bool              canonical;
+  bool              quiet;
+} Options;
 
+// Run the tool using the given options
 static SerdStatus
-read_file(SerdWorld* const      world,
-          const SerdSyntax      syntax,
-          const SerdReaderFlags flags,
-          SerdEnv* const        env,
-          const SerdSink* const sink,
-          const size_t          stack_size,
-          const char* const     filename,
-          const size_t          block_size)
+run(const Options opts)
 {
-  SerdInputStream in = serd_open_tool_input(filename);
-  if (!in.stream) {
-    SERDI_ERRORF(
-      "failed to open input file `%s' (%s)\n", filename, strerror(errno));
+  SerdTool app = {{NULL, NULL, NULL, NULL}, NULL, NULL, NULL};
 
-    return SERD_BAD_STREAM;
+  // Set up the writing environment
+  SerdStatus st = SERD_SUCCESS;
+  if ((st = serd_tool_setup(&app, "serd-pipe", opts.common))) {
+    serd_tool_cleanup(app);
+    return st;
   }
 
-  const SerdLimits limits = {stack_size, MAX_DEPTH};
-  serd_world_set_limits(world, limits);
+  if (opts.quiet) {
+    serd_set_log_func(app.world, serd_quiet_log_func, NULL);
+  }
 
-  SerdReader* reader = serd_reader_new(world, syntax, flags, env, sink);
-  SerdStatus  st     = serd_reader_start(reader, &in, NULL, block_size);
+  serd_writer_set_root_uri(app.writer, serd_string(opts.root_uri));
 
-  st = st ? st : serd_reader_read_document(reader);
+  // Set up the output pipeline: [canon] -> writer
+  const SerdSink* const target = serd_writer_sink(app.writer);
+  const SerdSink*       sink   = target;
+  SerdSink*             canon  = NULL;
+  if (opts.canonical) {
+    canon = serd_canon_new(app.world, target, opts.common.input.flags);
+    sink  = canon;
+  }
 
-  serd_reader_free(reader);
-  serd_close_input(&in);
+  if (opts.input_string) {
+    const char*     position = opts.input_string;
+    SerdInputStream in       = serd_open_input_string(&position);
 
-  return st;
-}
+    st = serd_read_source(
+      app.world,
+      opts.common,
+      app.env,
+      serd_choose_syntax(app.world, opts.common.input, NULL, SERD_TRIG),
+      &in,
+      "string",
+      sink);
 
-int
-main(int argc, char** argv)
-{
-  const char* const prog = argv[0];
-
-  SerdNode*       base          = NULL;
-  SerdSyntax      input_syntax  = SERD_SYNTAX_EMPTY;
-  SerdSyntax      output_syntax = SERD_SYNTAX_EMPTY;
-  SerdReaderFlags reader_flags  = 0;
-  SerdWriterFlags writer_flags  = 0;
-  bool            osyntax_set   = false;
-  bool            canonical     = false;
-  bool            quiet         = false;
-  size_t          block_size    = 4096U;
-  size_t          stack_size    = 1048576U;
-  const char*     input_string  = NULL;
-  const char*     root_uri      = NULL;
-  const char*     out_filename  = NULL;
-  int             a             = 1;
-  for (; a < argc && argv[a][0] == '-'; ++a) {
-    if (argv[a][1] == '\0') {
-      break;
-    }
+    serd_close_input(&in);
+  }
 
-    if (!strcmp(argv[a], "--help")) {
-      return print_usage(prog, false);
-    }
+  // Read all the inputs, which drives the writer to emit the output
+  if (st ||
+      (st = serd_read_inputs(
+         app.world, opts.common, app.env, opts.n_inputs, opts.inputs, sink)) ||
+      (st = serd_writer_finish(app.writer))) {
+    serd_sink_free(canon);
+    serd_tool_cleanup(app);
+    return st;
+  }
 
-    if (!strcmp(argv[a], "--version")) {
-      return serd_print_version(argv[0]);
-    }
+  serd_sink_free(canon);
+  return serd_tool_cleanup(app);
+}
 
-    for (int o = 1; argv[a][o]; ++o) {
-      const char opt = argv[a][o];
-
-      if (opt == 'C') {
-        canonical = true;
-      } else if (opt == 'h') {
-        return print_usage(prog, false);
-      } else if (opt == 'q') {
-        quiet = true;
-      } else if (opt == 'v') {
-        return serd_print_version(argv[0]);
-      } else if (argv[a][1] == 'B') {
-        if (++a == argc) {
-          return missing_arg(prog, 'B');
-        }
-
-        base = serd_node_new(NULL, serd_a_uri_string(argv[a]));
-        break;
-      } else if (opt == 'I') {
-        if (argv[a][o + 1] || ++a == argc) {
-          return missing_arg(prog, 'I');
-        }
-
-        if (serd_set_input_option(
-              serd_string(argv[a]), &input_syntax, &reader_flags)) {
-          return print_usage(argv[0], true);
-        }
-        break;
-      } else if (opt == 'O') {
-        if (argv[a][o + 1] || ++a == argc) {
-          return missing_arg(prog, 'O');
-        }
-
-        if (serd_set_output_option(
-              serd_string(argv[a]), &output_syntax, &writer_flags)) {
-          return print_usage(argv[0], true);
-        }
-
-        osyntax_set =
-          output_syntax != SERD_SYNTAX_EMPTY || !strcmp(argv[a], "empty");
-
-        break;
-      } else if (opt == 'b') {
-        if (argv[a][o + 1] || ++a == argc) {
-          return missing_arg(prog, 'b');
-        }
-
-        char*      endptr = NULL;
-        const long size   = strtol(argv[a], &endptr, 10);
-        if (size < 1 || size == LONG_MAX || *endptr != '\0') {
-          SERDI_ERRORF("invalid block size `%s'\n", argv[a]);
-          return 1;
-        }
-        block_size = (size_t)size;
-        break;
-      } else if (opt == 'k') {
-        if (argv[a][o + 1] || ++a == argc) {
-          return missing_arg(prog, 'k');
-        }
-
-        char*      endptr = NULL;
-        const long size   = strtol(argv[a], &endptr, 10);
-        if (size <= 0 || size == LONG_MAX || *endptr != '\0') {
-          SERDI_ERRORF("invalid stack size '%s'\n", argv[a]);
-          return 1;
-        }
-        stack_size = (size_t)size;
-        break;
-      } else if (opt == 'r') {
-        if (argv[a][o + 1] || ++a == argc) {
-          return missing_arg(prog, 'r');
-        }
-
-        root_uri = argv[a];
-        break;
-      } else if (opt == 's') {
-        if (argv[a][o + 1] || ++a == argc) {
-          return missing_arg(prog, 's');
-        }
-
-        input_string = argv[a];
-        break;
-      } else if (opt == 'w') {
-        if (argv[a][o + 1] || ++a == argc) {
-          return missing_arg(argv[0], 'w');
-        }
-
-        out_filename = argv[a];
-        break;
-      } else {
-        SERDI_ERRORF("invalid option -- '%s'\n", argv[a] + 1);
-        return print_usage(prog, true);
-      }
-    }
-  }
+/* Command-line interface (before setting up serd) */
 
-  if (a == argc && !input_string) {
-    SERDI_ERROR("missing input\n");
-    return print_usage(prog, true);
-  }
+static int
+print_usage(const char* const name, const bool error)
+{
+  static const char* const description =
+    "Read and write RDF data.\n"
+    "INPUT can be a local filename, or \"-\" to read from standard input.\n\n"
+    "  -B BASE_URI  Base URI or path for resolving relative references.\n"
+    "  -C           Convert literals to canonical form.\n"
+    "  -I SYNTAX    Input syntax turtle/ntriples/trig/nquads, or option\n"
+    "               lax/variables/relative/global/generated.\n"
+    "  -O SYNTAX    Output syntax empty/turtle/ntriples/nquads, or option\n"
+    "               ascii/expanded/verbatim/terse/lax.\n"
+    "  -R ROOT_URI  Keep relative URIs within ROOT_URI.\n"
+    "  -V           Display version information and exit.\n"
+    "  -b BYTES     I/O block size.\n"
+    "  -h           Display this help and exit.\n"
+    "  -k BYTES     Parser stack size.\n"
+    "  -o FILENAME  Write output to FILENAME instead of stdout.\n"
+    "  -q           Suppress warning and error output.\n"
+    "  -s STRING    Parse STRING as input.\n";
 
-  serd_set_stream_utf8_mode(stdin);
+  FILE* const os = error ? stderr : stdout;
+  fprintf(os, "%s", error ? "\n" : "");
+  fprintf(os, "Usage: %s [OPTION]... [INPUT]...\n", name);
+  fprintf(os, "%s", description);
+  return error;
+}
 
-  char* const* const inputs   = argv + a;
-  const int          n_inputs = argc - a;
+// Parse the option pointed to by `iter`, and advance it to the next one
+static SerdStatus
+parse_option(OptionIter* const iter, Options* const opts)
+{
+#define ARG_ERRORF(fmt, ...) \
+  fprintf(stderr, "%s: " fmt, iter->argv[0], __VA_ARGS__)
 
-  bool input_has_graphs = serd_syntax_has_graphs(input_syntax);
-  for (int i = a; i < argc; ++i) {
-    if (serd_syntax_has_graphs(serd_guess_syntax(argv[i]))) {
-      input_has_graphs = true;
-      break;
-    }
+  SerdStatus st = serd_parse_common_option(iter, &opts->common);
+  if (st != SERD_FAILURE) {
+    return st;
   }
 
-  if (!output_syntax && !osyntax_set) {
-    output_syntax = input_has_graphs ? SERD_NQUADS : SERD_NTRIPLES;
+  if (!strcmp(iter->argv[iter->a], "--help")) {
+    print_usage(iter->argv[0], false);
+    return SERD_FAILURE;
   }
 
-  if (!base && n_inputs == 1 &&
-      (output_syntax == SERD_NQUADS || output_syntax == SERD_NTRIPLES)) {
-    // Choose base URI from the single input path
-    char* const input_path = zix_canonical_path(NULL, inputs[0]);
-    if (!input_path ||
-        !(base = serd_node_new(
-            NULL,
-            serd_a_file_uri(serd_string(input_path), serd_empty_string())))) {
-      SERDI_ERRORF("unable to determine base URI from path %s\n", inputs[0]);
-    }
-    zix_free(NULL, input_path);
+  if (!strcmp(iter->argv[iter->a], "--version")) {
+    return serd_print_version(iter->argv[0]);
   }
 
-  SerdWorld* const world  = serd_world_new(NULL);
-  const SerdLimits limits = {stack_size, MAX_DEPTH};
-  serd_world_set_limits(world, limits);
-
-  SerdEnv* const env = serd_env_new(
-    NULL, base ? serd_node_string_view(base) : serd_empty_string());
+  const char opt = iter->argv[iter->a][iter->f];
+  switch (opt) {
+  case 'C':
+    opts->canonical = true;
+    return serd_option_iter_advance(iter);
 
-  SerdOutputStream out = serd_open_tool_output(out_filename);
-  if (!out.stream) {
-    perror("serdi: error opening output file");
-    return 1;
-  }
+  case 'R':
+    return serd_get_argument(iter, &opts->root_uri);
 
-  SerdWriter* const writer =
-    serd_writer_new(world, output_syntax, writer_flags, env, &out, block_size);
+  case 'V':
+    return serd_print_version("serd-pipe");
 
-  const SerdSink* sink = serd_writer_sink(writer);
+  case 'h':
+    print_usage(iter->argv[0], false);
+    return SERD_FAILURE;
 
-  SerdSink* canon = NULL;
-  if (canonical) {
-    sink = canon = serd_canon_new(world, sink, reader_flags);
-  }
+  case 'q':
+    opts->quiet = true;
+    return serd_option_iter_advance(iter);
 
-  if (quiet) {
-    serd_set_log_func(world, serd_quiet_log_func, NULL);
-  }
+  case 's':
+    return serd_get_argument(iter, &opts->input_string);
 
-  if (root_uri) {
-    serd_writer_set_root_uri(writer, serd_string(root_uri));
+  default:
+    break;
   }
 
-  SerdStatus st = SERD_SUCCESS;
-  if (input_string) {
-    const char*     position  = input_string;
-    SerdInputStream string_in = serd_open_input_string(&position);
+  ARG_ERRORF("invalid option -- '%c'\n", opt);
+  return SERD_BAD_ARG;
 
-    SerdReader* const reader = serd_reader_new(
-      world, input_syntax ? input_syntax : SERD_TRIG, reader_flags, env, sink);
+#undef ARG_ERRORF
+}
 
-    if (!(st = serd_reader_start(reader, &string_in, NULL, 1U))) {
-      st = serd_reader_read_document(reader);
+int
+main(const int argc, char* const* const argv)
+{
+  char  default_input[]  = {'-', '\0'};
+  char* default_inputs[] = {default_input};
+
+  Options opts = {{"",
+                   NULL,
+                   4096U,
+                   1048576U,
+                   {SERD_SYNTAX_EMPTY, 0U, false},
+                   {SERD_SYNTAX_EMPTY, 0U, false}},
+                  "",
+                  NULL,
+                  NULL,
+                  0U,
+                  false,
+                  false};
+
+  // Parse all command line options (which must precede inputs)
+  SerdStatus st   = SERD_SUCCESS;
+  OptionIter iter = {argv, argc, 1, 1};
+  while (!serd_option_iter_is_end(iter)) {
+    if ((st = parse_option(&iter, &opts))) {
+      return (st == SERD_FAILURE) ? 0 : print_usage(argv[0], true);
     }
-
-    serd_reader_free(reader);
-    serd_close_input(&string_in);
-  }
-
-  if (n_inputs == 1) {
-    reader_flags |= SERD_READ_GLOBAL;
   }
 
-  for (int i = 0; !st && i < n_inputs; ++i) {
-    if (!base && !!strcmp(inputs[i], "-")) {
-      if ((st = serd_set_base_uri_from_path(env, inputs[i]))) {
-        SERDI_ERRORF("failed to set base URI from path %s\n", inputs[i]);
-        break;
-      }
-    }
-
-    if ((st = read_file(world,
-                        serd_choose_syntax(world, input_syntax, inputs[i]),
-                        reader_flags,
-                        env,
-                        sink,
-                        stack_size,
-                        inputs[i],
-                        block_size))) {
-      break;
-    }
+  // Every argument past the last option is an input
+  opts.inputs   = argv + iter.a;
+  opts.n_inputs = argc - iter.a;
+  if (opts.n_inputs + (bool)opts.input_string == 0) {
+    opts.n_inputs = 1;
+    opts.inputs   = default_inputs;
   }
 
-  serd_sink_free(canon);
-  serd_writer_free(writer);
-  serd_env_free(env);
-  serd_node_free(NULL, base);
-  serd_world_free(world);
-
-  if (serd_close_output(&out)) {
-    perror("serd-pipe: write error");
-    st = SERD_BAD_STREAM;
+  // Don't add prefixes to blank node labels if there is only one input
+  if (opts.n_inputs + (bool)opts.input_string == 1) {
+    opts.common.input.flags |= SERD_READ_GLOBAL;
   }
 
-  return (st > SERD_FAILURE) ? 1 : 0;
+  return run(opts) > SERD_FAILURE;
 }