(read1): Redesign strategy for force_multibyte and

force_singlebyte.  Now is_multibyte records whether read_buffer
is multibyte.  Encountering any multibyte character makes it so.

1 files changed, 49 insertions, 40 deletions

diff --git a/src/lread.c b/src/lread.c
index ae8339ac3d0..10baf509918 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -2145,14 +2145,16 @@ read1 (readcharfun, pch, first_in_list)
         char *p = read_buffer;
         char *end = read_buffer + read_buffer_size;
         register int c;
-        /* Nonzero if we saw an escape sequence specifying
-           a multibyte character.  */
+        /* 1 if we saw an escape sequence specifying
+           a multibyte character, or a multibyte character.  */
         int force_multibyte = 0;
-        /* Nonzero if we saw an escape sequence specifying
+        /* 1 if we saw an escape sequence specifying
            a single-byte character.  */
         int force_singlebyte = 0;
+        /* 1 if read_buffer contains multibyte text now.  */
+        int is_multibyte = 0;
         int cancel = 0;
-        int nchars;
+        int nchars = 0;
 
         while ((c = READCHAR) >= 0
                && c != '\"')
@@ -2186,39 +2188,47 @@ read1 (readcharfun, pch, first_in_list)
                   force_multibyte = 1;
               }
 
-            if (! SINGLE_BYTE_CHAR_P ((c & ~CHAR_MODIFIER_MASK)))
+            /* A character that must be multibyte forces multibyte.  */
+            if (! SINGLE_BYTE_CHAR_P (c & ~CHAR_MODIFIER_MASK))
+              force_multibyte = 1;
+
+            /* If we just discovered the need to be multibyte,
+               convert the text accumulated thus far.  */
+            if (force_multibyte && ! is_multibyte)
               {
-                /* Any modifiers for a multibyte character are invalid.  */
-                if (c & CHAR_MODIFIER_MASK)
-                  error ("Invalid modifier in string");
-                p += CHAR_STRING (c, p);
-                force_multibyte = 1;
+                is_multibyte = 1;
+                to_multibyte (&p, &end, &nchars);
               }
-            else
-              {
-                /* Allow `\C- ' and `\C-?'.  */
-                if (c == (CHAR_CTL | ' '))
-                  c = 0;
-                else if (c == (CHAR_CTL | '?'))
-                  c = 127;
 
-                if (c & CHAR_SHIFT)
-                  {
-                    /* Shift modifier is valid only with [A-Za-z].  */
-                    if ((c & 0377) >= 'A' && (c & 0377) <= 'Z')
-                      c &= ~CHAR_SHIFT;
-                    else if ((c & 0377) >= 'a' && (c & 0377) <= 'z')
-                      c = (c & ~CHAR_SHIFT) - ('a' - 'A');
-                  }
+            /* Allow `\C- ' and `\C-?'.  */
+            if (c == (CHAR_CTL | ' '))
+              c = 0;
+            else if (c == (CHAR_CTL | '?'))
+              c = 127;
 
-                if (c & CHAR_META)
-                  /* Move the meta bit to the right place for a string.  */
-                  c = (c & ~CHAR_META) | 0x80;
-                if (c & ~0xff)
-                  error ("Invalid modifier in string");
-                *p++ = c;
+            if (c & CHAR_SHIFT)
+              {
+                /* Shift modifier is valid only with [A-Za-z].  */
+                if ((c & 0377) >= 'A' && (c & 0377) <= 'Z')
+                  c &= ~CHAR_SHIFT;
+                else if ((c & 0377) >= 'a' && (c & 0377) <= 'z')
+                  c = (c & ~CHAR_SHIFT) - ('a' - 'A');
               }
+
+            if (c & CHAR_META)
+              /* Move the meta bit to the right place for a string.  */
+              c = (c & ~CHAR_META) | 0x80;
+            if (c & CHAR_MODIFIER_MASK)
+              error ("Invalid modifier in string");
+
+            if (is_multibyte)
+              p += CHAR_STRING (c, p);
+            else
+              *p++ = c;
+
+            nchars++;
           }
+
         if (c < 0)
           end_of_file_error ();
 
@@ -2228,10 +2238,8 @@ read1 (readcharfun, pch, first_in_list)
         if (!NILP (Vpurify_flag) && NILP (Vdoc_file_name) && cancel)
           return make_number (0);
 
-        if (force_multibyte)
-          to_multibyte (&p, &end, &nchars);
-        else if (force_singlebyte)
-          nchars = p - read_buffer;
+        if (is_multibyte || force_singlebyte)
+          ;
         else if (load_convert_to_unibyte)
           {
             Lisp_Object string;
@@ -2242,6 +2250,8 @@ read1 (readcharfun, pch, first_in_list)
                                                 p - read_buffer);
                 return Fstring_make_unibyte (string);
               }
+            /* We can make a unibyte string directly.  */
+            is_multibyte = 0;
           }
         else if (EQ (readcharfun, Qget_file_char)
                  || EQ (readcharfun, Qlambda))
@@ -2252,19 +2262,18 @@ read1 (readcharfun, pch, first_in_list)
                for reading dynamic byte code (compiled with
                byte-compile-dynamic = t).  */
             to_multibyte (&p, &end, &nchars);
+            is_multibyte = 1;
           }
         else
           /* In all other cases, if we read these bytes as
              separate characters, treat them as separate characters now.  */
-          nchars = p - read_buffer;
+          ;
 
         if (read_pure)
           return make_pure_string (read_buffer, nchars, p - read_buffer,
-                                   (force_multibyte
-                                    || (p - read_buffer != nchars)));
+                                   is_multibyte);
         return make_specified_string (read_buffer, nchars, p - read_buffer,
-                                      (force_multibyte
-                                       || (p - read_buffer != nchars)));
+                                      is_multibyte);
       }
 
     case '.':