[regexp] string-only regexp matching

README.md

@@ -47,6 +47,5 @@ This library's [Scribble docs](TODO) give full details on the static checks.
 - `printf`
 
 #### `dependent/regexp`
-- `regexp-match?`
 - `regexp-match`
 

regexp.rkt

@@ -0,0 +1,73 @@
+#lang typed/racket/base
+
+(provide
+  regexp-match!
+  ;; (-> Pattern String Any * (U #f (List String *N+1)))
+  ;; Match the regular expression pattern against a string.
+  ;; If the pattern is determined statically, result will be either #f
+  ;;  or a list of N+1 strings, where N is the number of groups specified
+  ;;  the pattern.
+  ;;
+  ;; Will raise a compile-time exception if the pattern contains unmatched groups.
+)
+
+(require
+  (for-syntax racket/base syntax/parse racket/syntax))
+
+;; =============================================================================
+
+(define-syntax regexp-match!
+  (syntax-parser
+   [(f pat-stx arg* ...)
+    #:when (or (string? (syntax-e #'pat-stx))
+               (regexp? (syntax-e #'pat-stx)))
+    #:with num-groups (count-groups (format "~a" (syntax-e #'pat-stx)) #:src #'f)
+    #:with ((index* . group-id*) ...)
+           #`#,(for/list ([i (in-range (syntax-e #'num-groups))])
+                 (cons i (format-id #'f "group-~a" i)))
+    ;; Chaining list-ref?
+    #'(let ([m (regexp-match pat-stx arg* ...)])
+        (if m
+          (let ([group-id* (or (list-ref m index*) (error 'regexp-match! "Internal error, try Racket's `regexp-match`"))] ...)
+            (list (car m) group-id* ...))
+          m))]
+   [(f arg* ...)
+    (syntax/loc #'f (regexp-match arg* ...))]))
+
+(define-for-syntax (count-groups v #:src stx)
+  (cond
+   [(string? v)  (count-groups/string v #:src stx)]
+   [(regexp? v)  (count-groups/regexp v #:src stx)]
+   [else         (error 'regexp-match! "Internal error on input" v)]))
+
+;; Count the number of matched parentheses in a regexp pattern.
+;; Raise an exception if there are unmatched parens.
+(define-for-syntax (count-groups/string str #:src stx)
+  (define last-index (- (string-length str) 1))
+  (let loop ([i 0] [in-paren #f] [num-groups 0])
+    (if (> i last-index)
+      (if in-paren
+        (group-error str (format "'(' at index ~a" in-paren))
+        num-groups)
+      (case (string-ref str i)
+       [(#\()
+        (loop (+ i 1) i num-groups)]
+       [(#\))
+        (unless in-paren
+          (group-error str (format "')' at index ~a" i)))
+        (loop (+ i 1) #f (+ 1 num-groups))]
+       [(#\\)
+        (if (and (< i last-index) (eq? #\\ (string-ref str (+ i 1))))
+          (loop (+ i 3) in-paren num-groups)
+          (loop (+ i 2) in-paren num-groups))]
+       [else
+        (loop (+ i 1) in-paren num-groups)]))))
+
+(define-for-syntax (count-groups/regexp rxp #:src stx)
+  (error 'regexp-match! "Not implemented"))
+
+(define-for-syntax (group-error str reason)
+  (raise-argument-error
+    'regexp-match!
+    (format "Valid regexp pattern (contains unmatched ~a)" reason)
+    str))