[gnumeric] csv: improve separator guessing.

[Morten Welinder <mortenw src gnome org>]

commit a3bab97252708ace54f18796a07f1741ce533342
Author: Morten Welinder <terra gnome org>
Date:   Tue Apr 9 19:27:53 2019 -0400

    csv: improve separator guessing.
    
    Don't guess letters or digits.

 ChangeLog       |  5 +++++
 NEWS            |  1 +
 src/stf-parse.c | 30 ++++++++++++++++++++----------
 3 files changed, 26 insertions(+), 10 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index f62478899..07a2b6fba 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-04-09  Morten Welinder  <terra gnome org>
+
+       * src/stf-parse.c (stf_parse_options_guess_csv): Avoid guessing
+       insane separators.  Fixes #397.
+
 2019-01-15  Morten Welinder  <terra gnome org>
 
        * src/mathfunc.c (gnm_lambert_w): Avoid static for something that
diff --git a/NEWS b/NEWS
index 3118262ba..6ddd66662 100644
--- a/NEWS
+++ b/NEWS
@@ -6,6 +6,7 @@ Eugen Dedu:
 Morten:
        * Add DIGAMMA function.
        * Support ISO-8601 UTC date/time input.  Mostly.  [#371]
+       * Improve cvs separator guessing.  [#397]
 
 Thomas Klausner:
        * Fix compilation issue.  [#378]
diff --git a/src/stf-parse.c b/src/stf-parse.c
index 11009b90a..135de8662 100644
--- a/src/stf-parse.c
+++ b/src/stf-parse.c
@@ -1735,23 +1735,29 @@ stf_parse_options_guess_csv (char const *data)
        lines_chunk = g_string_chunk_new (100 * 1024);
        lines = stf_parse_lines (res, lines_chunk, data, 1000, FALSE);
 
-       /*
-        * Find a line containing a quote; skip first line unless it is
-        * the only one.  Prefer a line with the quote first.
-        */
-       for (pass = 1; !quoteline && pass <= 2; pass++) {
+       // Find a line containing a quote; skip first line unless it is
+       // the only one.  Prefer a line with the quote first.
+       //
+       // Pass 1: look for initial quote, but not on first line
+       // Pass 2: look for initial quote on first line
+       // Pass 3: look for quote anywhere in any line
+       for (pass = 1; !quoteline && pass <= 3; pass++) {
                size_t lno;
-               for (lno = MIN (1, lines->len - 1);
-                    !quoteline && lno < lines->len;
+               size_t lstart = (pass == 1 ? 1 : 0);
+               size_t lend = (pass == 2 ? 1 : -1);
+
+               for (lno = lstart;
+                    !quoteline && lno < MIN (lend, lines->len);
                     lno++) {
                        GPtrArray *boxline = g_ptr_array_index (lines, lno);
                        const char *line = g_ptr_array_index (boxline, 0);
                        switch (pass) {
                        case 1:
+                       case 2:
                                if (g_utf8_get_char (line) == stringind)
                                        quoteline = line;
                                break;
-                       case 2:
+                       case 3:
                                if (my_utf8_strchr (line, stringind))
                                        quoteline = line;
                                break;
@@ -1763,6 +1769,9 @@ stf_parse_options_guess_csv (char const *data)
                const char *p0 = my_utf8_strchr (quoteline, stringind);
                const char *p = p0;
 
+               if (gnm_debug_flag ("stf"))
+                       g_printerr ("quoteline = [%s]\n", quoteline);
+
                do {
                        p = g_utf8_next_char (p);
                } while (*p && g_utf8_get_char (p) != stringind);
@@ -1770,8 +1779,9 @@ stf_parse_options_guess_csv (char const *data)
                while (*p && g_unichar_isspace (g_utf8_get_char (p)))
                        p = g_utf8_next_char (p);
                if (*p) {
-                       /* Use the character after the quote.  */
-                       sep = g_strndup (p, g_utf8_next_char (p) - p);
+                       // Use the character after the quote.
+                       if (g_unichar_ispunct (g_utf8_get_char (p)))
+                               sep = g_strndup (p, g_utf8_next_char (p) - p);
                } else {
                        /* Try to use character before the quote.  */
                        while (p0 > quoteline && !sep) {