song/StringFilter: support regular expressions with "=~" and "!~"

This feature requires `libpcre`.

src/lib/pcre/RegexPointer.hxx

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2007-2018 Content Management AG
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef REGEX_POINTER_HXX
+#define REGEX_POINTER_HXX
+
+#include "util/StringView.hxx"
+#include "util/Compiler.h"
+
+#include <pcre.h>
+
+#include <array>
+
+class RegexPointer {
+protected:
+	pcre *re = nullptr;
+	pcre_extra *extra = nullptr;
+
+	unsigned n_capture = 0;
+
+public:
+	constexpr bool IsDefined() const noexcept {
+		return re != nullptr;
+	}
+
+	gcc_pure
+	bool Match(StringView s) const noexcept {
+		/* we don't need the data written to ovector, but PCRE can
+		   omit internal allocations if we pass a buffer to
+		   pcre_exec() */
+		std::array<int, 16> ovector;
+		return pcre_exec(re, extra, s.data, s.size,
+				 0, 0, &ovector.front(), ovector.size()) >= 0;
+	}
+};
+
+#endif

src/lib/pcre/UniqueRegex.cxx

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2007-2018 Content Management AG
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "UniqueRegex.hxx"
+#include "util/RuntimeError.hxx"
+
+void
+UniqueRegex::Compile(const char *pattern, bool anchored, bool capture,
+		     bool caseless)
+{
+	constexpr int default_options = PCRE_DOTALL|PCRE_NO_AUTO_CAPTURE|PCRE_UTF8;
+
+	int options = default_options;
+	if (anchored)
+		options |= PCRE_ANCHORED;
+	if (capture)
+		options &= ~PCRE_NO_AUTO_CAPTURE;
+	if (caseless)
+		options |= PCRE_CASELESS;
+
+	const char *error_string;
+	int error_offset;
+	re = pcre_compile(pattern, options, &error_string, &error_offset, nullptr);
+	if (re == nullptr)
+		throw FormatRuntimeError("Error in regex at offset %d: %s",
+					 error_offset, error_string);
+
+	int study_options = 0;
+#ifdef PCRE_CONFIG_JIT
+	study_options |= PCRE_STUDY_JIT_COMPILE;
+#endif
+	extra = pcre_study(re, study_options, &error_string);
+	if (extra == nullptr && error_string != nullptr) {
+		pcre_free(re);
+		re = nullptr;
+		throw FormatRuntimeError("Regex study error: %s", error_string);
+	}
+
+	int n;
+	if (capture && pcre_fullinfo(re, extra, PCRE_INFO_CAPTURECOUNT, &n) == 0)
+		n_capture = n;
+}

src/lib/pcre/UniqueRegex.hxx

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2007-2018 Content Management AG
+ * All rights reserved.
+ *
+ * author: Max Kellermann <mk@cm4all.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef UNIQUE_REGEX_HXX
+#define UNIQUE_REGEX_HXX
+
+#include "RegexPointer.hxx"
+#include "util/StringView.hxx"
+
+#include <algorithm>
+
+#include <pcre.h>
+
+class UniqueRegex : public RegexPointer {
+public:
+	UniqueRegex() = default;
+
+	UniqueRegex(const char *pattern, bool anchored, bool capture,
+		    bool caseless) {
+		Compile(pattern, anchored, capture, caseless);
+	}
+
+	UniqueRegex(UniqueRegex &&src) noexcept:RegexPointer(src) {
+		src.re = nullptr;
+		src.extra = nullptr;
+	}
+
+	~UniqueRegex() noexcept {
+		pcre_free(re);
+#ifdef PCRE_CONFIG_JIT
+		pcre_free_study(extra);
+#else
+		pcre_free(extra);
+#endif
+	}
+
+	UniqueRegex &operator=(UniqueRegex &&src) {
+		using std::swap;
+		swap<RegexPointer>(*this, src);
+		return *this;
+	}
+
+	/**
+	 * Throws std::runtime_error on error.
+	 */
+	void Compile(const char *pattern, bool anchored, bool capture,
+		     bool caseless);
+};
+
+#endif

src/lib/pcre/meson.build

@@ -0,0 +1,21 @@
+pcre_dep = dependency('libpcre', required: get_option('pcre'))
+conf.set('HAVE_PCRE', pcre_dep.found())
+if not pcre_dep.found()
+  subdir_done()
+endif
+
+pcre = static_library(
+  'pcre',
+  'UniqueRegex.cxx',
+  include_directories: inc,
+  dependencies: [
+    pcre_dep,
+  ],
+)
+
+pcre_dep = declare_dependency(
+  link_with: pcre,
+  dependencies: [
+    pcre_dep,
+  ],
+)