From 8be5386075f93a2b79f31edecb6a5d3527f3d9bf Mon Sep 17 00:00:00 2001
From: Eatswap <root@eatswap.org>
Date: Mon, 12 Dec 2022 23:20:25 +0800
Subject: [PATCH] add: introduce AST

---
 AST.cpp   |   7 ++
 AST.h     | 226 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 Makefile  |   3 +-
 context.h |  34 ++++++++
 types.h   |  17 ++++
 value.h   | 175 ++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 461 insertions(+), 1 deletion(-)
 create mode 100644 AST.cpp
 create mode 100644 AST.h
 create mode 100644 context.h
 create mode 100644 types.h
 create mode 100644 value.h

diff --git a/AST.cpp b/AST.cpp
new file mode 100644
index 0000000..502cf2e
--- /dev/null
+++ b/AST.cpp
@@ -0,0 +1,7 @@
+#include <utility>
+
+#include "AST.h"
+
+namespace DragonLisp {
+
+} // end of namespace DragonLisp
diff --git a/AST.h b/AST.h
new file mode 100644
index 0000000..c08f8a6
--- /dev/null
+++ b/AST.h
@@ -0,0 +1,226 @@
+#ifndef __DRAGON_LISP_AST_H__
+#define __DRAGON_LISP_AST_H__
+
+#include <memory>
+#include <variant>
+
+#include "types.h"
+#include "token.h"
+#include "context.h"
+
+namespace DragonLisp {
+
+enum ASTType {
+	T_ArrayRefAST,
+	T_IdentifierAST,
+	T_FuncDefAST,
+	T_FuncCallAST,
+	T_IfAST,
+	T_LoopAST,
+	T_UnaryAST,
+	T_BinaryAST,
+	T_ListAST,
+	T_VarOpAST,
+	T_LValOpAST,
+};
+
+/// BaseAST - Base class for all AST nodes.
+class BaseAST {
+public:
+	virtual ~BaseAST() = default;
+
+	virtual ASTType getType() const = 0;
+};
+
+class ExprAST : public BaseAST {
+public:
+	virtual std::shared_ptr<Value> eval(Context* parent) = 0;
+};
+
+class LValueAST : public ExprAST {
+public:
+	virtual std::shared_ptr<Value> set(Context* parent, std::shared_ptr<Value> value) = 0;
+};
+
+class ArrayRefAST : public LValueAST {
+private:
+	std::string name;
+	std::shared_ptr<ExprAST> index;
+
+public:
+	ArrayRefAST(std::string name, std::shared_ptr<ExprAST> index) : name(std::move(name)), index(std::move(index)) {}
+
+	ASTType getType() const override final {
+		return T_ArrayRefAST;
+	}
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	std::shared_ptr<Value> set(Context* parent, std::shared_ptr<Value> value) override final;
+};
+
+class IdentifierAST : public LValueAST {
+private:
+	std::string name;
+
+public:
+	explicit IdentifierAST(std::string name) : name(std::move(name)) {}
+
+	ASTType getType() const override final {
+		return T_IdentifierAST;
+	}
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	std::shared_ptr<Value> set(Context* parent, std::shared_ptr<Value> value) override final;
+};
+
+class FuncDefAST : public BaseAST {
+private:
+	std::string name;
+	std::vector<std::string> args;
+	std::vector<std::shared_ptr<ExprAST>> body;
+
+public:
+	FuncDefAST(std::string name, std::vector<std::string> args, std::vector<std::shared_ptr<ExprAST>> body) : name(std::move(name)), args(std::move(args)), body(std::move(body)) {}
+
+	std::shared_ptr<Value> eval(Context* parent, std::vector<std::shared_ptr<Value>> arg);
+
+	inline ASTType getType() const override final {
+		return T_FuncDefAST;
+	}
+};
+
+class FuncCallAST : public ExprAST {
+private:
+	std::string name;
+	std::vector<std::shared_ptr<ExprAST>> args;
+
+public:
+	FuncCallAST(std::string name, std::vector<std::unique_ptr<ExprAST>> args);
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	inline ASTType getType() const override final {
+		return T_FuncCallAST;
+	}
+};
+
+class IfAST : public ExprAST {
+private:
+	std::shared_ptr<ExprAST> cond;
+	std::shared_ptr<ExprAST> then;
+	std::shared_ptr<ExprAST> els;
+
+public:
+	IfAST(std::unique_ptr<ExprAST> cond, std::unique_ptr<ExprAST> then, std::unique_ptr<ExprAST> els);
+
+	std::shared_ptr<Value> eval(Context* parent) override final {
+		throw std::runtime_error("You should use IfAST::getResult() instead of IfAST::eval()");
+	}
+
+	std::shared_ptr<ExprAST> getResult(Context* parent);
+
+	inline ASTType getType() const override final {
+		return T_IfAST;
+	}
+};
+
+class LoopAST : public ExprAST {
+private:
+	std::string loopVar;
+	std::shared_ptr<ExprAST> start;
+	std::shared_ptr<ExprAST> end;
+	std::shared_ptr<FuncDefAST> body;
+
+public:
+	LoopAST(std::string loopVar, std::unique_ptr<ExprAST> start, std::unique_ptr<ExprAST> end, std::unique_ptr<FuncDefAST> body);
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	inline ASTType getType() const override final {
+		return T_LoopAST;
+	}
+};
+
+class UnaryAST : public ExprAST {
+private:
+	std::shared_ptr<ExprAST> expr;
+	Token op;
+
+public:
+	UnaryAST(std::unique_ptr<ExprAST> expr, Token op);
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	inline ASTType getType() const override final {
+		return T_UnaryAST;
+	}
+};
+
+class BinaryAST : public ExprAST {
+private:
+	std::shared_ptr<ExprAST> lhs;
+	std::shared_ptr<ExprAST> rhs;
+	Token op;
+
+public:
+	BinaryAST(std::unique_ptr<ExprAST> lhs, std::unique_ptr<ExprAST> rhs, Token op);
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	inline ASTType getType() const override final {
+		return T_BinaryAST;
+	}
+};
+
+class ListAST : public ExprAST {
+private:
+	std::vector<std::shared_ptr<ExprAST>> exprs;
+	Token op;
+
+public:
+	ListAST(std::vector<std::unique_ptr<ExprAST>> exprs, Token op);
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	inline ASTType getType() const override final {
+		return T_ListAST;
+	}
+};
+
+class VarOpAST : public ExprAST {
+private:
+	std::string name;
+	std::shared_ptr<ExprAST> expr;
+	Token op;
+
+public:
+	VarOpAST(std::string name, std::unique_ptr<ExprAST> expr, Token op);
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	inline ASTType getType() const override final {
+		return T_VarOpAST;
+	}
+};
+
+class LValOpAST : public ExprAST {
+private:
+	std::shared_ptr<ExprAST> lval;
+	std::shared_ptr<ExprAST> expr;
+	Token op;
+
+public:
+	LValOpAST(std::unique_ptr<ExprAST> lval, std::unique_ptr<ExprAST> expr, Token op);
+
+	std::shared_ptr<Value> eval(Context* parent) override final;
+
+	inline ASTType getType() const override final {
+		return T_LValOpAST;
+	}
+};
+
+}
+
+#endif // __DRAGON_LISP_AST_H__
diff --git a/Makefile b/Makefile
index e4251d5..11389b2 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ COMMONFLAGS ?= -g -Wall
 CFLAGS ?= $(COMMONFLAGS) -std=c18
 CXXFLAGS ?= $(COMMONFLAGS) -std=c++20
 
-MISCOBJ = main DragonLispDriver
+MISCOBJ = main DragonLispDriver AST
 OBJS  = $(addsuffix .o, $(MISCOBJ))
 
 all: compile
@@ -49,6 +49,7 @@ compile_debug: lexer parser
 	$(CXX) $(CXXFLAGS) -o $(OUTPUT) \
 		main.cpp \
 		DragonLispDriver.cpp \
+		AST.cpp \
 		DragonLisp.tab.cc \
 		lex.yy.cc
 
diff --git a/context.h b/context.h
new file mode 100644
index 0000000..0c0868e
--- /dev/null
+++ b/context.h
@@ -0,0 +1,34 @@
+#ifndef __DRAGON_LISP_CONTEXT_H__
+#define __DRAGON_LISP_CONTEXT_H__
+
+#include <memory>
+#include <variant>
+
+#include "value.h"
+
+namespace DragonLisp {
+
+class FuncDefAST;
+
+class Context {
+private:
+	std::unordered_map<std::string, std::shared_ptr<Value>> variables;
+
+	Context* parent = nullptr;
+
+	std::unordered_map<std::string, std::shared_ptr<FuncDefAST>>* funcs = nullptr;
+
+public:
+	explicit Context(Context* p = nullptr) : parent(p) {
+		this->funcs = p ? p->funcs : new std::unordered_map<std::string, std::shared_ptr<FuncDefAST>>;
+	}
+
+	~Context() {
+		if (!this->parent)
+			delete this->funcs;
+	}
+};
+
+}
+
+#endif // __DRAGON_LISP_CONTEXT_H__
diff --git a/types.h b/types.h
new file mode 100644
index 0000000..11cd152
--- /dev/null
+++ b/types.h
@@ -0,0 +1,17 @@
+#ifndef __DRAGON_LISP_TYPES_H__
+#define __DRAGON_LISP_TYPES_H__
+
+namespace DragonLisp {
+
+enum ValueType {
+	TYPE_INTEGER,
+	TYPE_FLOAT,
+	TYPE_STRING,
+	TYPE_ARRAY,
+	TYPE_T,		// has no value
+	TYPE_NIL,	// has no value
+};
+
+} // namespace DragonLisp
+
+#endif // __DRAGON_LISP_TYPES_H__
diff --git a/value.h b/value.h
new file mode 100644
index 0000000..96f5f14
--- /dev/null
+++ b/value.h
@@ -0,0 +1,175 @@
+#ifndef __DRAGON_LISP_VALUE_H__
+#define __DRAGON_LISP_VALUE_H__
+
+#include <variant>
+#include <cstdint>
+#include <string>
+
+#include "types.h"
+
+namespace DragonLisp {
+
+using ValueVariant = std::variant<std::monostate, std::int64_t, double, std::string>;
+
+class Value {
+public:
+	virtual bool isArray() const = 0;
+};
+
+class ArrayValue : public Value {
+private:
+	std::vector<ValueVariant> values;
+
+	std::size_t size;
+
+public:
+	ArrayValue() = delete;
+
+	explicit ArrayValue(std::size_t s) : values(s), size(s) {}
+
+	explicit ArrayValue(std::vector<ValueVariant> v) : values(std::move(v)), size(this->values.size()) {}
+
+	bool isArray() const override final {
+		return true;
+	}
+
+	std::size_t getSize() const {
+		return this->size;
+	}
+
+	ValueVariant& operator[](std::size_t i) {
+		return this->values[i];
+	}
+
+	const ValueVariant& operator[](std::size_t i) const {
+		return this->values[i];
+	}
+
+	std::vector<ValueVariant>& getValues() {
+		return this->values;
+	}
+
+	const std::vector<ValueVariant>& getValues() const {
+		return this->values;
+	}
+};
+
+class SingleValue : public Value {
+private:
+	ValueType type;
+
+	ValueVariant value;
+
+	explicit SingleValue(ValueType t) : type(t), value() {}
+
+public:
+	explicit SingleValue(std::int64_t v) : value(v) {}
+
+	explicit SingleValue(double v) : value(v) {}
+
+	explicit SingleValue(std::string v) : value(std::move(v)) {}
+
+	SingleValue() = delete;
+
+	bool isArray() const override final {
+		return false;
+	}
+
+	static SingleValue makeT() {
+		return SingleValue(ValueType::TYPE_T);
+	}
+
+	static SingleValue makeNil() {
+		return SingleValue(ValueType::TYPE_NIL);
+	}
+
+	ValueType getType() const {
+		return this->type;
+	}
+
+	bool isT() const {
+		return this->type == ValueType::TYPE_T;
+	}
+
+	bool isNil() const {
+		return this->type == ValueType::TYPE_NIL;
+	}
+
+	bool isInt() const {
+		return std::holds_alternative<std::int64_t>(this->value);
+	}
+
+	bool isFloat() const {
+		return std::holds_alternative<double>(this->value);
+	}
+
+	bool isString() const {
+		return std::holds_alternative<std::string>(this->value);
+	}
+
+	std::int64_t getInt() const {
+		return std::get<std::int64_t>(this->value);
+	}
+
+	double getFloat() const {
+		return std::get<double>(this->value);
+	}
+
+	std::string getString() const {
+		return std::get<std::string>(this->value);
+	}
+
+	ValueVariant getValue() const {
+		return this->value;
+	}
+
+	void setValue(ValueVariant v) {
+		this->value = std::move(v);
+	}
+};
+
+class _Unused_Variable {
+protected:
+	std::string name;
+
+	std::variant<ArrayValue, SingleValue> val;
+
+public:
+	_Unused_Variable() = delete;
+
+	_Unused_Variable(std::string n, SingleValue v) : name(std::move(n)), val(std::move(v)) {}
+
+	_Unused_Variable(std::string n, ArrayValue v) : name(std::move(n)), val(std::move(v)) {}
+
+	std::string getName() const {
+		return this->name;
+	}
+
+	bool isArray() const {
+		return std::holds_alternative<ArrayValue>(this->val);
+	}
+
+	bool isValue() const {
+		return std::holds_alternative<SingleValue>(this->val);
+	}
+
+	ArrayValue getArray() const {
+		return std::get<ArrayValue>(this->val);
+	}
+
+	SingleValue getValue() const {
+		return std::get<SingleValue>(this->val);
+	}
+
+	void set(SingleValue v) {
+		this->val = std::move(v);
+	}
+
+	void set(ArrayValue v) {
+		this->val = std::move(v);
+	}
+};
+
+}
+
+#endif // __DRAGON_LISP_VALUE_H__