gie: implement a strict_mode command

In that mode:
* All non-comment/decoration lines must start with a valid tag
* Commands split on several lines should be terminated with " \"

src/apps/gie.cpp

@@ -123,7 +123,7 @@ Thomas Knudsen, thokn@sdfe.dk, 2017-10-01/2017-10-08
 /* Package for flexible format I/O - ffio */
 typedef struct ffio {
     FILE *f;
-    const char **tags;
+    const char * const *tags;
     const char *tag;
     char *args;
     char *next_args;
@@ -144,10 +144,10 @@ static int at_end_delimiter (ffio *G);
 static const char *at_tag (ffio *G);
 static int at_decorative_element (ffio *G);
 static ffio *ffio_destroy (ffio *G);
-static ffio *ffio_create (const char **tags, size_t n_tags, size_t max_record_size);
+static ffio *ffio_create (const char * const *tags, size_t n_tags, size_t max_record_size);
 
-static const char *gie_tags[] = {
-    "<gie>", "operation", "crs_src", "crs_dst", "use_proj4_init_rules",
+static const char * const gie_tags[] = {
+    "<gie>", "strict_mode", "operation", "crs_src", "crs_dst", "use_proj4_init_rules",
     "accept", "expect", "roundtrip", "banner", "verbose",
     "direction", "tolerance", "ignore", "require_grid", "echo", "skip", "</gie>"
 };
@@ -179,6 +179,7 @@ typedef struct {
     PJ *P;
     PJ_COORD a, b, c, e;
     PJ_DIRECTION dir;
+    bool strict_mode;
     int verbosity;
     int skip;
     int op_id;
@@ -1061,6 +1062,7 @@ Indicate that the remaining material should be skipped. Mostly for debugging.
 static int dispatch (const char *cmnd, const char *args) {
     if (T.skip)
         return SKIP;
+    if  (0==strcmp (cmnd, "strict_mode"))   { T.strict_mode = true; return 0; }
     if  (0==strcmp (cmnd, "operation")) return  operation ((char *) args);
     if  (0==strcmp (cmnd, "crs_src"))   return  crs_src   (args);
     if  (0==strcmp (cmnd, "crs_dst"))   return  crs_dst   (args);
@@ -1267,7 +1269,7 @@ See the PROJ ".gie" test suites for examples of supported formatting.
 
 
 /***************************************************************************************/
-static ffio *ffio_create (const char **tags, size_t n_tags, size_t max_record_size) {
+static ffio *ffio_create (const char * const *tags, size_t n_tags, size_t max_record_size) {
 /****************************************************************************************
 Constructor for the ffio object.
 ****************************************************************************************/
@@ -1514,6 +1516,45 @@ whitespace etc. The block is stored in G->args. Returns 1 on success, 0 otherwis
 ****************************************************************************************/
     G->args[0] = 0;
 
+    // Special parsing in strict_mode:
+    // - All non-comment/decoration lines must start with a valid tag
+    // - Commands split on several lines should be terminated with " \"
+    if( T.strict_mode )
+    {
+        while( nextline(G) )
+        {
+            G->lineno = G->next_lineno;
+            if( G->next_args[0] == 0 || at_decorative_element(G) ) {
+                continue;
+            }
+            G->tag = at_tag (G);
+            if (nullptr==G->tag)
+            {
+                fprintf (T.fout, "unsupported command line %d: %s\n", (int)G->lineno, G->next_args);
+                return 0;
+            }
+
+            append_args (G);
+            pj_shrink (G->args);
+            while( G->args[strlen(G->args)-1] == '\\' )
+            {
+                G->args[strlen(G->args)-1] = 0;
+                if( !nextline(G) )
+                {
+                    return 0;
+                }
+                G->lineno = G->next_lineno;
+                append_args (G);
+                pj_shrink (G->args);
+            }
+            if ( 0==strcmp (G->tag, "</gie>")) {
+                G->level++;
+            }
+            return 1;
+        }
+        return 0;
+    }
+
     if (0==skip_to_next_tag (G))
         return 0;
     G->tag = at_tag (G);