Add expand command as described in POSIX-2008.

Erratum: Do not handle backspace.

1 files changed, 141 insertions, 0 deletions

diff --git a/toys/posix/expand.c b/toys/posix/expand.c
new file mode 100644
index 00000000..739c326d
--- /dev/null
+++ b/toys/posix/expand.c
@@ -0,0 +1,141 @@
+/* expand.c - expands tabs to space
+ *
+ * FIXME: handle backspace.
+ *
+ * Copyright 2012 Jonathan Clairembault <jonathan at clairembault dot fr>
+ *
+ * See http://http://pubs.opengroup.org/onlinepubs/9699919799/nframe.html
+
+USE_EXPAND(NEWTOY(expand, "t:", TOYFLAG_USR|TOYFLAG_BIN))
+
+config EXPAND
+  bool "expand"
+  default n
+  help
+    usage: expand [-t tablist] [file...]
+
+    Command expand. Expands tabs to space according to tabstops.
+
+    -t  tablist
+    Specify the tab stops.  The argument tablist consists of either a single 
+    strictly positive decimal integer or a list of tabstops. If a single number 
+    is given, tabs are set that number of column positions apart instead of the 
+    default 8.
+
+    If a list of tabstops is given, the list is made of two or more strictly 
+    positive decimal integers, separated by <blank> or <comma> characters, in 
+    strictly ascending order. The <tab> characters are set at those specific 
+    column positions.
+
+    In the event of expand having to process a <tab> at a position beyond the 
+    last of those specified in a multiple tab-stop list, the <tab> is replaced 
+    by a single <space> in the output.
+
+    Any <backspace> characters shall be copied to the output and cause the 
+    column position count for tab stop calculations to be decremented; the 
+    column position count shall not be decremented below zero.
+*/
+
+#define FOR_expand
+#include "toys.h"
+
+GLOBALS(
+  char *t_flags;
+  struct offset_list tablist;
+)
+
+static void build_tablist(char *tabstops)
+{
+  char *ctx;
+  struct offset_list *tablist = &TT.tablist;
+  char *s, *ref;
+  off_t stop, last_stop;
+
+  /* for every tabstop decode and add to list */
+  for (stop = last_stop = 0, s = ref = xstrdup(tabstops); ;
+       last_stop = stop, s = NULL) {
+    char *tabstop = strtok_r(s, " ,", &ctx);
+
+    if (!tabstop) return;
+
+    stop = xstrtoul(tabstop, NULL, 0);
+    if (stop <= last_stop) {
+      free(ref);
+      toys.exithelp = 1;
+      error_exit("tablist ascending order");
+    }
+    tablist->next = xzalloc(sizeof(*tablist));
+    tablist->next->off = stop;
+    tablist = tablist->next;
+  }
+
+  free(ref);
+}
+
+static void expand_file(int fd, char *name)
+{
+  ssize_t rdn;
+  char *rdbuf, *wrbuf;
+  size_t wrbuflen, rdbuflen;
+  ssize_t rdbufi = 0, wrbufi = 0;
+  ssize_t wrlinei;
+  int hastablist = !!TT.tablist.next->next;
+  struct offset_list *tablist = TT.tablist.next;
+  ssize_t stop = tablist->off;
+
+  wrbuflen = rdbuflen = ARRAY_LEN(toybuf)/2;
+  rdbuf = toybuf;
+  wrbuf = toybuf + rdbuflen;
+  do {
+    rdn = readall(fd, rdbuf, rdbuflen);
+    if (rdn < 0) perror_exit("%s", name);
+    for (rdbufi=0, wrbufi=0; rdbufi<rdn; rdbufi++) {
+      if (wrbufi == wrbuflen) { /* flush expand buffer when full */
+        writeall(STDOUT_FILENO, wrbuf, wrbuflen);
+        wrbufi = 0;
+      }
+      if (rdbuf[rdbufi] == '\t') { /* expand tab */
+        size_t count;
+        size_t tabsize;
+
+        /* search next tab stop */
+        while(tablist && (stop <= wrlinei)) {
+          stop = hastablist ? tablist->off : stop + tablist->off;
+          tablist = hastablist ? tablist->next : tablist;
+        }
+        tabsize = ((stop - wrlinei < 2)) ? 1 : stop - wrlinei;
+        while (tabsize) { /* long expand */
+          count = min(tabsize, wrbuflen - wrbufi);
+          memset(wrbuf + wrbufi, ' ', count);
+          tabsize -= count;
+          if (tabsize) { /* flush expand buffer when full */
+            writeall(STDOUT_FILENO, wrbuf, wrbuflen);
+            wrbufi = 0;
+          } else wrbufi += count;
+        }
+        wrlinei += count;
+      } else { /* copy input to output */
+        wrbuf[wrbufi++] = rdbuf[rdbufi];
+        wrlinei += 1;
+        /* flush expand buffer and reset tablist at newline */
+        if (rdbuf[rdbufi] == '\n') {
+          writeall(STDOUT_FILENO, wrbuf, wrbufi);
+          tablist = TT.tablist.next;
+          stop = tablist->off;
+          wrbufi = wrlinei = 0;
+        }
+      }
+    }
+  } while (rdn == rdbuflen);
+  /* flush last expand buffer */
+  writeall(STDOUT_FILENO, wrbuf, wrbufi);
+}
+
+void expand_main(void)
+{
+  build_tablist((toys.optflags & FLAG_t) ? TT.t_flags : "8");
+  /* expand every file */
+  loopfiles(toys.optargs, expand_file);
+  /* free tablist */
+  llist_traverse(TT.tablist.next, free);
+}