Shell: Add a (very basic) formatter

Shell/Formatter.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 "NodeVisitor.h"
+#include <AK/Forward.h>
+#include <AK/StringBuilder.h>
+#include <AK/StringView.h>
+#include <AK/Types.h>
+#include <AK/Vector.h>
+#include <ctype.h>
+
+class Formatter final : public AST::NodeVisitor {
+public:
+    Formatter(const StringView& source, ssize_t cursor = -1)
+        : m_builder(round_up_to_power_of_two(source.length(), 16))
+        , m_source(source)
+        , m_cursor(cursor)
+    {
+        size_t offset = 0;
+        for (auto ptr = m_source.end() - 1; ptr >= m_source.begin() && isspace(*ptr); --ptr)
+            ++offset;
+
+        m_trivia = m_source.substring_view(m_source.length() - offset, offset);
+    }
+
+    String format();
+    size_t cursor() const { return m_output_cursor; }
+
+private:
+    virtual void visit(const AST::PathRedirectionNode*) override;
+    virtual void visit(const AST::And*) override;
+    virtual void visit(const AST::ListConcatenate*) override;
+    virtual void visit(const AST::Background*) override;
+    virtual void visit(const AST::BarewordLiteral*) override;
+    virtual void visit(const AST::CastToCommand*) override;
+    virtual void visit(const AST::CastToList*) override;
+    virtual void visit(const AST::CloseFdRedirection*) override;
+    virtual void visit(const AST::CommandLiteral*) override;
+    virtual void visit(const AST::Comment*) override;
+    virtual void visit(const AST::DynamicEvaluate*) override;
+    virtual void visit(const AST::DoubleQuotedString*) override;
+    virtual void visit(const AST::Fd2FdRedirection*) override;
+    virtual void visit(const AST::FunctionDeclaration*) override;
+    virtual void visit(const AST::ForLoop*) override;
+    virtual void visit(const AST::Glob*) override;
+    virtual void visit(const AST::Execute*) override;
+    virtual void visit(const AST::IfCond*) override;
+    virtual void visit(const AST::Join*) override;
+    virtual void visit(const AST::MatchExpr*) override;
+    virtual void visit(const AST::Or*) override;
+    virtual void visit(const AST::Pipe*) override;
+    virtual void visit(const AST::ReadRedirection*) override;
+    virtual void visit(const AST::ReadWriteRedirection*) override;
+    virtual void visit(const AST::Sequence*) override;
+    virtual void visit(const AST::Subshell*) override;
+    virtual void visit(const AST::SimpleVariable*) override;
+    virtual void visit(const AST::SpecialVariable*) override;
+    virtual void visit(const AST::Juxtaposition*) override;
+    virtual void visit(const AST::StringLiteral*) override;
+    virtual void visit(const AST::StringPartCompose*) override;
+    virtual void visit(const AST::SyntaxError*) override;
+    virtual void visit(const AST::Tilde*) override;
+    virtual void visit(const AST::VariableDeclarations*) override;
+    virtual void visit(const AST::WriteAppendRedirection*) override;
+    virtual void visit(const AST::WriteRedirection*) override;
+
+    void test_and_update_output_cursor(const AST::Node*);
+    void insert_separator();
+    void insert_indent();
+
+    ALWAYS_INLINE void with_added_indent(int indent, Function<void()>);
+    ALWAYS_INLINE void in_new_block(Function<void()>);
+
+    StringBuilder& current_builder() { return m_builder; }
+
+    struct Options {
+        size_t max_line_length_hint { 80 };
+        bool explicit_parentheses { false };
+        bool explicit_braces { false };
+        bool in_double_quotes { false };
+    } m_options;
+
+    size_t m_current_line_length { 0 };
+    size_t m_current_indent { 0 };
+
+    StringBuilder m_builder;
+
+    StringView m_source;
+    size_t m_output_cursor { 0 };
+    ssize_t m_cursor { -1 };
+    AST::Node* m_hit_node { nullptr };
+
+    const AST::Node* m_parent_node { nullptr };
+
+    StringView m_trivia;
+};