From 94fbf2ab94d7021f113604c898a718ce74f58076 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Mon, 19 Nov 2018 17:36:23 -0800
Subject: [PATCH] that wasn't too bad

---
 pitfall/ptest/check-pdf.rkt | 101 +++++++++++++++++++++++++-----------
 pitfall/ptest/pushy.rkt     |  24 ---------
 2 files changed, 70 insertions(+), 55 deletions(-)
 delete mode 100644 pitfall/ptest/pushy.rkt

diff --git a/pitfall/ptest/check-pdf.rkt b/pitfall/ptest/check-pdf.rkt
index 4c90520f..35d4a2c0 100644
--- a/pitfall/ptest/check-pdf.rkt
+++ b/pitfall/ptest/check-pdf.rkt
@@ -17,37 +17,73 @@
        #'(cond
            [(regexp-try-match (pregexp (string-append "^" PAT)) PORT) . REST] ... [else ELSE-CLAUSE]))]))
 
-(define (parse-1 x)
-  (pat-lex x
-           ["\\s+" (parse-1 x)] ; whitespace
-           ["\\d+ 0 obj" (parse-1 x)] ;; obj name
-           ["(<<\n.*\n>>)\\s*stream\n" ; dict with stream
-            => (λ (m)
-                 (define d (parse-1 (open-input-bytes (cadr m))))
-                 (define stream-length
-                   (read (open-input-bytes (cdr (assoc #"/Length" d)))))
-                 (define stream (read-bytes stream-length x))
-                 (append d (list (cons 'stream stream))))]
-           ["<<\n(.*)\n>>" ;; dict
-            => (λ (m)
-                 (define items (parse-pdf-bytes (cadr m)))
-                 (unless (even? (length items))
-                   (raise items))
-                 (sort ; put hash into order so it's comparable
-                  (for/list ([kv (in-slice 2 items)])
-                    (apply cons kv))
-                  bytes<?
-                  #:key car))]
-           ["\\[(.*?)\\]" => (compose1 parse-pdf-bytes cadr)] ;; list
-           ["\\d+ 0 R"] ; xref
-           ["[-]?\\d+"] ; number
-           ["\\(.*?\\)"] ; parenstring
-           ["/\\S+"] ; keystring
-           [else eof]))
+(define (between-delimiters bs left right)
+  (parameterize ([current-input-port (if (input-port? bs) bs (open-input-bytes bs))])
+    (let loop ([acc null][depth 0])
+      (cond
+        [(regexp-try-match (pregexp (string-append "^" (regexp-quote (~a left)))) (current-input-port))
+         => (λ (m)
+              (loop (if (empty? acc)
+                        acc ; impliedly throw away first left delimiter
+                        (cons (car m) acc)) (add1 depth)))]
+        [(regexp-try-match (pregexp (string-append "^" (regexp-quote (~a right)))) (current-input-port)) 
+         => (λ (m)
+              (case depth
+                [(1) (bytes-append* (reverse acc))]
+                [else (loop (cons (car m) acc) (sub1 depth))]))]
+        [else
+         (define bstr (read-byte))
+         (and (not (eof-object? bstr))
+              (loop (if (zero? depth)
+                        acc ; impliedly throw away leading non-delimiter bytes
+                        (cons (bytes bstr) acc)) depth))]))))
+
+(module+ test
+  (require rackunit)
+  (define bs #"a<<b<<c>>x<<z>>d>>e<<f>>g")
+  (check-equal? (between-delimiters bs #"<<" #">>") #"b<<c>>x<<z>>d")
+  (check-equal? (between-delimiters (between-delimiters bs #"<<" #">>") #"<<" #">>") #"c")
+  (check-false (between-delimiters #"abc" #"<<" #">>"))
+  (check-equal? (between-delimiters #"[a[b]c]" #"[" #"]") #"a[b]c")
+  (check-equal? (let ([ip (open-input-bytes #"<</foo 42>>z")])
+                  (parse-1 ip)
+                  (port->bytes ip)) #"z"))
+
+(define (parse-1 ip)
+  (cond
+    ;; the complication is that arrays & dicts can contain other arrays & dicts
+    ;; so we have to scan ahead in an intelligent way.
+    [(equal? (peek-bytes 1 0 ip) #"[") ;; array
+     (parse-pdf-bytes (between-delimiters ip #"[" #"]"))]
+    [(equal? (peek-bytes 2 0 ip) #"<<") ;; dict, maybe with stream
+     (define items (parse-pdf-bytes (between-delimiters ip #"<<" #">>")))
+     (unless (even? (length items)) (raise items))
+     (define dic
+       (sort ; put hash into order so it's comparable
+        (for/list ([kv (in-slice 2 items)])
+                  (apply cons kv))
+        bytes<?
+        #:key car))
+     (cond
+       [(regexp-try-match #px"^\\s*stream\n" ip)
+        (define stream-length
+          (read (open-input-bytes (cdr (assoc #"/Length" dic)))))
+        (define stream (read-bytes stream-length ip))
+        (append dic (list (cons 'stream stream)))]
+       [else dic])]
+    [else
+     (pat-lex ip
+              ["\\s+" (parse-1 ip)] ; whitespace
+              ["\\d+ 0 obj" (parse-1 ip)] ;; obj name
+              ["\\d+ 0 R"] ; xref
+              ["[-]?\\d+"] ; number
+              ["\\(.*?\\)"] ; parenstring
+              ["/\\S+"] ; keystring
+              [else eof])]))
 
 (define (parse-pdf-bytes bs)
   (for/list ([tok (in-port parse-1 (open-input-bytes bs))])
-    tok))
+            tok))
 
 (define (pdf->dict pdf)
   (define pdf-bs (file->bytes pdf))
@@ -59,17 +95,20 @@
      (sort ; sort by byte offset
       (cdr ; drop zeroth record: there is no zeroth object
        (for/list ([i (in-range ref-count)])
-         (cons i (read (open-input-bytes (car (regexp-match #px"\\d{10}" xref-ip)))))))
+                 (cons i (read (open-input-bytes (car (regexp-match #px"\\d{10}" xref-ip)))))))
       < #:key cdr)
      (list (cons #f xoff))))
   (sort ; sort by index
    (parameterize ([current-input-port (open-input-bytes pdf-bs)])
      (for/list ([(idx start) (in-dict obj-locations)]
                 [(_ end) (in-dict (cdr obj-locations))])
-       (cons idx (parse-pdf-bytes (peek-bytes (- end start) start)))))
+               (cons idx (parse-pdf-bytes (peek-bytes (- end start) start)))))
    < #:key car))
 
 (define-simple-check (check-pdfs-equal? ps1 ps2)
   (equal? (pdf->dict ps1) (pdf->dict ps2)))
 
-
+(for ([p (in-directory)]
+      #:when (path-has-extension? p #"pdf"))
+     (with-handlers ([exn:fail? (λ (exn) (println (format "~a failed" p)))])
+       (pdf->dict p)))
diff --git a/pitfall/ptest/pushy.rkt b/pitfall/ptest/pushy.rkt
deleted file mode 100644
index 1fd90676..00000000
--- a/pitfall/ptest/pushy.rkt
+++ /dev/null
@@ -1,24 +0,0 @@
-#lang debug br
-(require racket/bytes)
-
-
-(define (outer-delimiter bs left right)
-  (parameterize ([current-input-port (open-input-bytes bs)])
-    (let loop ([acc null][depth 0])
-      (cond
-        [(regexp-try-match (regexp (format "^~a" left)) (current-input-port))
-         => (λ (m) (loop (cons (car m) acc) (add1 depth)))]
-        [(regexp-try-match (regexp (format "^~a" right)) (current-input-port)) 
-         => (λ (m)
-              (case depth
-                [(= depth 1) (apply bytes-append (reverse (cons (car m) acc)))]
-                [else (loop (cons (car m) acc) (sub1 depth))]))]
-        [else
-         (define b (read-byte))
-         (loop (if (empty? acc)
-                   acc ; drop leading non-delimiter bytes
-                   (cons (bytes b) acc)) depth)]))))
-
-(define bs #"aaa<<bbb<<ccc>>xxx<<zzz>>ddd>>eee<<fff>>ggg")
-
-(outer-delimiter bs #"<<" #">>")
\ No newline at end of file