From 0cf982a577e43e660de6fbff155d50315a66119e Mon Sep 17 00:00:00 2001
From: Mustafa Quraish <mustafaq9@gmail.com>
Date: Fri, 28 Jan 2022 10:01:30 -0500
Subject: Add AST/type definitions

Just the basic building blocks for now, probably need to re-think
how these are stored.
---
 cup/ast.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 cup/ast.h | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 142 insertions(+)
 create mode 100644 cup/ast.c
 create mode 100644 cup/ast.h

diff --git a/cup/ast.c b/cup/ast.c
new file mode 100644
index 0000000..2f3d94d
--- /dev/null
+++ b/cup/ast.c
@@ -0,0 +1,71 @@
+#include "ast.h"
+#include <assert.h>
+#include <stdio.h>
+
+char *data_type_to_str(DataType type)
+{
+    switch (type)
+    {
+    case TYPE_NONE: return "void";
+    case TYPE_INT: return "int";
+    default: assert(false && "Unreachable");
+    }
+}
+
+char *node_type_to_str(NodeType type)
+{
+    switch (type)
+    {
+    #define ENUM_TOKEN(t, name) case t: return name;
+        ENUM_AST_TYPES(ENUM_TOKEN)
+    #undef ENUM_TOKEN
+    default: assert(false && "Unreachable");
+    }
+}
+
+static void do_print_ast(Node *node, int depth)
+{
+    for (int i = 0; i < depth; i++) {
+        printf("  ");
+    }
+    if (node->type == AST_PROGRAM) {
+        for (int i = 0; i < node->block.num_children; i++) {
+            do_print_ast(node->block.children[i], depth);
+        }
+    } else if (node->type == AST_BLOCK) {
+        printf("{\n");
+        for (int i = 0; i < node->block.num_children; i++) {
+            do_print_ast(node->block.children[i], depth + 1);
+        }
+        for (int i = 0; i < depth; i++) {
+            printf("  ");
+        }
+        printf("}\n");
+    } else if (node->type == AST_FUNC) {
+        printf("fn %s()", node->func.name);
+        if (node->func.return_type.type != TYPE_NONE) {
+            // FIXME: Print return type properly
+            Type t = node->func.return_type;
+            printf(" -> %s", data_type_to_str(t.type));
+            for (int i = 0; i < t.indirection; i++) {
+                printf("*");
+            }
+
+        }
+        printf("\n");
+        do_print_ast(node->func.body, depth + 1);
+    } else if (node->type == AST_LITERAL) {
+        printf("(literal %d)\n", node->literal.as_int);
+    } else if (node->type == AST_RETURN) {
+        printf("return\n");
+        do_print_ast(node->unary_expr, depth + 1);
+    } else {
+        printf("(unknown)\n");
+    }
+}
+
+
+void print_ast(Node *node)
+{
+    do_print_ast(node, 0);
+}
\ No newline at end of file
diff --git a/cup/ast.h b/cup/ast.h
new file mode 100644
index 0000000..6170489
--- /dev/null
+++ b/cup/ast.h
@@ -0,0 +1,71 @@
+#pragma once
+
+#include <stdbool.h>
+
+#define ENUM_AST_TYPES(F)                                                      \
+  F(OP_PLUS, "+")                                                              \
+  F(OP_MINUS, "-")                                                             \
+  F(OP_MUL, "*")                                                               \
+  F(OP_DIV, "/")                                                               \
+  F(AST_LITERAL, "literal")                                                    \
+  F(AST_RETURN, "return")                                                      \
+  F(AST_FUNC, "func")                                                          \
+  F(AST_PROGRAM, "program")                                                    \
+  F(AST_BLOCK, "block statements")                                             \
+
+
+typedef enum {
+#define DEFINE_ENUM(name, str) name,
+  ENUM_AST_TYPES(DEFINE_ENUM)
+#undef DEFINE_ENUM
+} NodeType;
+
+char *node_type_to_str(NodeType type);
+
+typedef enum {
+    TYPE_NONE,
+    TYPE_INT,
+} DataType;
+
+char *data_type_to_str(DataType type);
+
+typedef struct {
+    DataType type;
+    // 0 = value, 1 = pointer, 2 = double pointer, ...
+    int indirection;
+} Type;
+
+typedef struct ast_node Node;
+typedef struct ast_node {
+    NodeType type;
+
+    union {
+        // Binary expr
+        struct {
+            Node *left;
+            Node *right;
+        } binary;
+        // Unary expr
+        Node *unary_expr;
+        // Function definition
+        struct {
+            char *name;
+            Type return_type;
+            Node *body;
+            // TODO: Arguments / etc?
+        } func;
+        // Block of statements
+        struct {
+            Node **children;
+            int num_children;
+        } block;
+        struct {
+            Type type;
+            union {
+                int as_int;
+            };
+        } literal;
+    };
+} Node;
+
+void print_ast(Node *node);
\ No newline at end of file
-- 
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