use a scheme procedures+eval to manage and transform AST

Removes records for a more-managable scheme-syntax approach. Modules+overriding allows for the IR itself to be represented and evaluated as scheme code during each transformation.

1 files changed, 35 insertions, 0 deletions

diff --git a/src/modules/parser/driver.scm b/src/modules/parser/driver.scm
new file mode 100644
index 0000000..8fd42a4
--- /dev/null
+++ b/src/modules/parser/driver.scm
@@ -0,0 +1,35 @@
+(define-module (modules parser driver)
+  #:use-module (ice-9 match)
+  #:export (tokens->ast))
+
+
+(define (die)
+  (error "syntax error"))
+
+(define (tokens->ast tokens)
+  (match tokens
+    ((func ...)
+     (list 'prog (function func)))
+    (_ (die))))
+
+(define (function tokens)
+  (match tokens
+    (('int (? string? id) 'left-paren 'void 'right-paren 'open-brace stmt ... 'close-brace)
+     (list 'func id (statement stmt)))
+    (_ (die))))
+
+(define (statement tokens)
+  (match tokens
+    (('return expr ... 'semi-colon)
+     (list 'stmt (expression expr)))
+    (_ (die))))
+
+(define (expression tokens)
+  (match tokens
+    (((? integer? int))
+     int)
+    (((or 'neg 'not) expr ...)
+     (list 'expr (car tokens) (expression expr)))
+    (('left-paren expr ... 'right-paren)
+     (expression expr))
+    (_ (die))))