[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- removed all the unit tests (most were outdated)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

2 files changed, 56 insertions, 0 deletions

diff --git a/src/backend/emitter/driver.scm b/src/backend/emitter/driver.scm
new file mode 100644
index 0000000..bd65d5a
--- /dev/null
+++ b/src/backend/emitter/driver.scm
@@ -0,0 +1,6 @@
+(define-module (backend emitter driver)
+  #:export (assembly->string))
+
+
+(define (assembly->string n)
+  (eval n (resolve-module '(backend emitter traverse))))
diff --git a/src/backend/emitter/traverse.scm b/src/backend/emitter/traverse.scm
new file mode 100644
index 0000000..0a5b4cc
--- /dev/null
+++ b/src/backend/emitter/traverse.scm
@@ -0,0 +1,50 @@
+(define-module (backend emitter traverse)
+  #:export (prog
+            subrout
+            instr
+            allocate
+            mov
+            ret
+            neg
+            not
+            allocate
+            reg
+            stack
+            imm))
+
+
+(define (prog srout)
+  (string-append/shared srout ".section .note.GNU-stack,\"\",@progbits\n"))
+
+(define (srout label instrs)
+  (format #f "    .globl ~a
+~a:
+\tpushq\t%rbp
+\tmovq\t%rsp, %rbp
+~a" label label (apply string-append/shared instrs)))
+
+(define (mov src dst)
+  (format #f "\tmovl\t~a, ~a\n" src dst))
+
+(define (ret)
+  "\tmovq\t%rbp, %rsp
+\tpopq\t%rbp
+\tret\n")
+
+(define (neg dst)
+  (format #f "\tnegl\t~a\n" dst))
+
+(define (not dst)
+  (format #f "\tnotl\t~a\n" dst))
+
+(define (alloc size)
+  (format #f "\tsubq\t$~a, %rsp\n" size))
+
+(define (reg r)
+  (format #f "%~a" r))
+
+(define (stack loc)
+  (format #f "~a(%rbp)" loc))
+
+(define (imm int)
+  (format #f "$~a" int))