[Ongoing] Rewrite frontend to use Flex/Bison

This is a merge of another experiment, so the changes are large:

- separated "modules" directory into frontend/backend
  - adjusted module names and moved files for this to happen
- removed modules lexer & parser
- removed all the unit tests (most were outdated)
- added Bison, flex, and C development tools to manifest.scm
- added lexer.l, a source file used by the flex utility with a functioning lexing implementation
- added parser.y, a source file used by the bison utility with a functioning parser implementation
- added node.c and node.h, which parser.y uses to construct an AST of a C source file (up to binary ops)
- added driver.c, a Guile-C interface that provides a module to scheme programs
- added a Makefile to make all of this
- added stuff to .gitignore

1 files changed, 33 insertions, 0 deletions

diff --git a/src/frontend/node.h b/src/frontend/node.h
new file mode 100644
index 0000000..71c8182
--- /dev/null
+++ b/src/frontend/node.h
@@ -0,0 +1,33 @@
+#ifndef NODE_H
+#define NODE_H
+
+#include <stddef.h>
+
+enum node_type{PROG, FUNC, STMT, EXPR, CONST};
+enum node_op{COMP_SYM, NEG_SYM, PLUS_SYM, MINUS_SYM, MULT_SYM, DIV_SYM, MOD_SYM};
+
+extern const char* node_types[];
+extern const char* node_ops[];
+
+typedef union {
+  char *name;
+  int val;
+  enum node_op op;
+} node_field;
+
+typedef struct Node {
+  enum node_type type;
+  node_field field;
+  struct Node **children;
+  size_t num_children;
+} Node;
+
+Node *create_node(enum node_type type);
+Node *create_function(char *name);
+Node *create_expr(enum node_op op);
+Node *create_const(int val);
+void add_child(Node *parent, Node *child);
+void free_node(Node *node);
+void *print_node(Node *node, int indent);
+
+#endif