jitters: ast: add ast definitions

src/ast/ast.c

@@ -0,0 +1,64 @@
+#include "ast.h"
+
+#include <stdlib.h>
+#include <err.h>
+
+static void *xmalloc(size_t size)
+{
+    void *ret = malloc(size);
+
+    if (ret == NULL)
+        err(1, NULL);
+
+    return ret;
+}
+
+struct ast_node *make_num(int val)
+{
+    struct ast_node *ret = xmalloc(sizeof(*ret));
+
+    ret->kind = NUM;
+    ret->val.num = val;
+
+    return ret;
+}
+
+struct ast_node *make_unop(enum unop_kind op, struct ast_node *rhs)
+{
+    struct ast_node *ret = xmalloc(sizeof(*ret));
+
+    ret->kind = UNOP;
+    ret->val.un_op.op = op;
+    ret->val.un_op.rhs = rhs;
+
+    return ret;
+}
+
+struct ast_node *make_binop(enum binop_kind op, struct ast_node *lhs,
+                            struct ast_node *rhs)
+{
+    struct ast_node *ret = xmalloc(sizeof(*ret));
+
+    ret->kind = BINOP;
+    ret->val.bin_op.op = op;
+    ret->val.bin_op.lhs = lhs;
+    ret->val.bin_op.rhs = rhs;
+
+    return ret;
+}
+
+void destroy_ast(struct ast_node *ast)
+{
+    if (!ast)
+        return;
+
+    if (ast->kind == BINOP)
+    {
+        destroy_ast(ast->val.bin_op.lhs);
+        destroy_ast(ast->val.bin_op.rhs);
+    }
+    else if (ast->kind == UNOP)
+        destroy_ast(ast->val.un_op.rhs);
+
+    free(ast);
+}

src/ast/ast.h

@@ -0,0 +1,59 @@
+#ifndef AST_H
+#define AST_H
+
+// Forward declaration
+struct ast_node;
+
+enum unop_kind
+{
+    IDENTITY,
+    NEGATE,
+};
+
+enum binop_kind
+{
+    PLUS,
+    MINUS,
+    TIMES,
+    DIVIDE,
+};
+
+struct unop_node
+{
+    enum unop_kind op;
+    struct ast_node *rhs;
+};
+
+struct binop_node
+{
+    enum binop_kind op;
+    struct ast_node *lhs;
+    struct ast_node *rhs;
+};
+
+struct ast_node
+{
+    enum node_kind
+    {
+        UNOP,
+        BINOP,
+        NUM,
+    } kind;
+    union ast_val
+    {
+        struct unop_node un_op;
+        struct binop_node bin_op;
+        int num;
+    } val;
+};
+
+struct ast_node *make_num(int val);
+
+struct ast_node *make_unop(enum unop_kind op, struct ast_node *rhs);
+
+struct ast_node *make_binop(enum binop_kind op, struct ast_node *lhs,
+                            struct ast_node *rhs);
+
+void destroy_ast(struct ast_node *ast);
+
+#endif /* !AST_H */

src/ast/local.am

@@ -0,0 +1,4 @@
+jitters_SOURCES += \
+    %D%/ast.c \
+    %D%/ast.h \
+    $(NULL)

src/local.am

@@ -14,4 +14,5 @@ AM_CPPFLAGS = -I$(top_builddir)/src -I$(srcdir)
 # Initialise those variables for use in included files
 jitters_LDADD =
 
+include %D%/ast/local.am
 include %D%/parse/local.am