AK: Add SourceGenerator class.

2 files changed, 206 insertions, 0 deletions

diff --git a/AK/SourceGenerator.h b/AK/SourceGenerator.h
new file mode 100644
index 0000000000..c212926861
--- /dev/null
+++ b/AK/SourceGenerator.h
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. 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 COPYRIGHT HOLDER 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.
+ */
+
+#pragma once
+
+#include <AK/GenericLexer.h>
+#include <AK/HashMap.h>
+#include <AK/String.h>
+#include <AK/StringBuilder.h>
+
+namespace AK {
+
+class SourceGenerator {
+public:
+    using MappingType = HashMap<StringView, String>;
+
+    explicit SourceGenerator(SourceGenerator& parent, char opening = '@', char closing = '@')
+        : m_parent(&parent)
+        , m_opening(opening)
+        , m_closing(closing)
+    {
+    }
+    explicit SourceGenerator(char opening = '@', char closing = '@')
+        : m_parent(nullptr)
+        , m_opening(opening)
+        , m_closing(closing)
+    {
+        m_builder = new StringBuilder();
+    }
+
+    void set(StringView key, String value) { m_mapping.set(key, value); }
+
+    String lookup(StringView key) const
+    {
+        if (auto opt = m_mapping.get(key); opt.has_value())
+            return opt.value();
+
+        if (m_parent == nullptr) {
+            dbgln("Can't find key '{}'", key);
+            ASSERT_NOT_REACHED();
+        }
+
+        return m_parent->lookup(key);
+    }
+
+    String generate() const { return builder().build(); }
+
+    StringBuilder& builder()
+    {
+        if (m_parent)
+            return m_parent->builder();
+        else
+            return *m_builder;
+    }
+    const StringBuilder& builder() const
+    {
+        if (m_parent)
+            return m_parent->builder();
+        else
+            return *m_builder;
+    }
+
+    void append(StringView pattern)
+    {
+        GenericLexer lexer { pattern };
+
+        while (!lexer.is_eof()) {
+            // FIXME: It is a bit inconvinient, that 'consume_until' also consumes the 'stop' character, this makes
+            //        the method less generic because there is no way to check if the 'stop' character ever appeared.
+            const auto consume_until_without_consuming_stop_character = [&](char stop) {
+                return lexer.consume_while([&](char ch) { return ch != stop; });
+            };
+
+            builder().append(consume_until_without_consuming_stop_character(m_opening));
+
+            if (lexer.consume_specific(m_opening)) {
+                const auto placeholder = consume_until_without_consuming_stop_character(m_closing);
+
+                if (!lexer.consume_specific(m_closing))
+                    ASSERT_NOT_REACHED();
+
+                builder().append(lookup(placeholder));
+            } else {
+                ASSERT(lexer.is_eof());
+            }
+        }
+    }
+
+private:
+    SourceGenerator* m_parent;
+    MappingType m_mapping;
+    OwnPtr<StringBuilder> m_builder;
+    char m_opening, m_closing;
+};
+
+}
+
+using AK::SourceGenerator;
diff --git a/AK/Tests/TestSourceGenerator.cpp b/AK/Tests/TestSourceGenerator.cpp
new file mode 100644
index 0000000000..e686faa5c2
--- /dev/null
+++ b/AK/Tests/TestSourceGenerator.cpp
@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. 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 COPYRIGHT HOLDER 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 <AK/TestSuite.h>
+
+#include <AK/SourceGenerator.h>
+
+TEST_CASE(generate_c_code)
+{
+    SourceGenerator generator;
+    generator.set("name", "foo");
+
+    generator.append("const char* @name@ (void) { return \"@name@\"; }");
+
+    EXPECT_EQ(generator.generate(), "const char* foo (void) { return \"foo\"; }");
+}
+
+TEST_CASE(scoped)
+{
+    SourceGenerator global_generator;
+
+    global_generator.append("\n");
+
+    global_generator.set("foo", "foo-0");
+    global_generator.set("bar", "bar-0");
+    global_generator.append("@foo@ @bar@\n"); // foo-0 bar-0
+
+    {
+        SourceGenerator scoped_generator_1 { global_generator };
+
+        scoped_generator_1.set("bar", "bar-1");
+        global_generator.append("@foo@ @bar@\n"); // foo-0 bar-0
+    }
+
+    global_generator.append("@foo@ @bar@\n"); // foo-0 bar-0
+
+    {
+        SourceGenerator scoped_generator_2 { global_generator };
+
+        scoped_generator_2.set("foo", "foo-2");
+        scoped_generator_2.append("@foo@ @bar@\n"); // foo-2 bar-0
+
+        {
+            // FIXME: This is never put onto the output?
+
+            SourceGenerator scoped_generator_3 { scoped_generator_2 };
+            scoped_generator_3.set("bar", "bar-3");
+            scoped_generator_3.append("@foo@ @bar@\n"); // foo-2 bar-3
+        }
+
+        {
+            SourceGenerator scoped_generator_4 { global_generator };
+            scoped_generator_4.append("@foo@ @bar@\n"); // foo-0 bar-0
+        }
+
+        scoped_generator_2.append("@foo@ @bar@\n"); // foo-2 bar-0
+    }
+
+    EXPECT_EQ(global_generator.generate(), "\nfoo-0 bar-0\nfoo-0 bar-0\nfoo-0 bar-0\nfoo-2 bar-0\nfoo-2 bar-3\nfoo-0 bar-0\nfoo-2 bar-0\n");
+}
+
+TEST_MAIN(SourceGenerator)