Everywhere: Start implementation of step2

src/environment.h

@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2023 Riyyi
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+#include <cstdint> // int64_t
+#include <iostream>
+#include <span>
+#include <string_view>
+#include <unordered_map>
+#include <vector>
+
+#include "error.h"
+#include "ruc/format/color.h"
+#include "ruc/singleton.h"
+
+#include "ast.h"
+#include "types.h"
+
+namespace blaze {
+
+class Environment {
+public:
+	Environment() = default;
+	virtual ~Environment() = default;
+
+	ASTNode* lookup(const std::string& symbol)
+	{
+		m_current_key = symbol;
+		return m_values.find(symbol) != m_values.end() ? m_values[symbol] : nullptr;
+	}
+
+protected:
+	std::string m_current_key;
+	std::unordered_map<std::string, ASTNode*> m_values;
+};
+
+class GlobalEnvironment final : public Environment {
+public:
+	GlobalEnvironment()
+	{
+		auto add = [](std::span<ASTNode*> nodes) -> ASTNode* {
+			int64_t result = 0;
+
+			for (auto node : nodes) {
+				if (!is<Number>(node)) {
+					Error::the().addError(format("wrong type argument: number-or-marker-p, '{}'", node));
+					return nullptr;
+				}
+
+				result += static_cast<Number*>(node)->number();
+			}
+
+			return new Number(result);
+		};
+
+		auto sub = [](std::span<ASTNode*> nodes) -> ASTNode* {
+			int64_t result = 0;
+
+			if (nodes.size() == 0) {
+				return new Number(0);
+			}
+
+			for (auto node : nodes) {
+				if (!is<Number>(node)) {
+					Error::the().addError(format("wrong type argument: number-or-marker-p, '{}'", node));
+					return nullptr;
+				}
+			}
+
+			// Start with the first number
+			result += static_cast<Number*>(nodes[0])->number();
+
+			// Skip the first node
+			for (auto it = std::next(nodes.begin()); it != nodes.end(); ++it) {
+				result -= static_cast<Number*>(*it)->number();
+			}
+
+			return new Number(result);
+		};
+
+		auto mul = [](std::span<ASTNode*> nodes) -> ASTNode* {
+			int64_t result = 1;
+
+			for (auto node : nodes) {
+				if (!is<Number>(node)) {
+					Error::the().addError(format("wrong type argument: number-or-marker-p, '{}'", node));
+					return nullptr;
+				}
+
+				result *= static_cast<Number*>(node)->number();
+			}
+
+			return new Number(result);
+		};
+
+		auto div = [this](std::span<ASTNode*> nodes) -> ASTNode* {
+			double result = 0;
+
+			if (nodes.size() == 0) {
+				Error::the().addError(format("wrong number of arguments: {}, 0", m_current_key));
+				return nullptr;
+			}
+
+			for (auto node : nodes) {
+				if (!is<Number>(node)) {
+					Error::the().addError(format("wrong type argument: number-or-marker-p, '{}'", node));
+					return nullptr;
+				}
+			}
+
+			// Start with the first number
+			result += static_cast<Number*>(nodes[0])->number();
+
+			// Skip the first node
+			for (auto it = std::next(nodes.begin()); it != nodes.end(); ++it) {
+				result /= static_cast<Number*>(*it)->number();
+			}
+
+			return new Number((int64_t)result);
+		};
+
+		m_values.emplace("+", new Function(add));
+		m_values.emplace("-", new Function(sub));
+		m_values.emplace("*", new Function(mul));
+		m_values.emplace("/", new Function(div));
+	}
+	virtual ~GlobalEnvironment() = default;
+};
+
+} // namespace blaze
+
+// associative data structure that maps symbols (the keys) to values
+
+// values = anything, including other symbols.
+// an environment is like a hash table
+
+// value can map to:
+// list
+// vector
+// hash-map
+// symbol
+// number
+// string
+// function