lib.c (subst): Make the big table a bit more comprehensible.

[runlisp] / lib.c

diff --git a/lib.c b/lib.c
index b509cea..c844997 100644 (file)
--- a/lib.c
+++ b/lib.c
@@ -1251,7 +1251,7 @@ void config_read_env(struct config *conf, struct config_section *sect)
  *
  * This only keeps track of the immutable parameters for the substitution
  * task: stuff which changes (flags, filtering state, cursor position) is
- *      maintained separately.
+ * maintained separately.
  */
 struct subst {
   struct config *config;               /* configuration state */
@@ -1384,7 +1384,8 @@ static const char *subst(const char *p, const char *l,
    * us which special characters we need to stop at.  This way, we can use
    * `strcspn' to skip over literal text and stop at the next character which
    * needs special handling.  Entries in this table with a null pointer
-   * correspond to impossible flag settings.
+   * correspond to impossible flag settings: notably, `SF_QUOT' can only be
+   * set when `SF_SUBST' is also set.
    */
   static const char *const delimtab[] = {
 
@@ -1396,26 +1397,27 @@ static const char *subst(const char *p, const char *l,
                                         * `SF_QUOT' */
 #define DELIM "|}"                     /* end delimiters of `SF_SUBEXPR' */
 
-    ESCAPE,
-    ESCAPE            WORDSEP,
-    0,
-    ESCAPE            QUOT,
-    ESCAPE      SUBST,
-    ESCAPE      SUBST WORDSEP,
-    0,
-    ESCAPE      SUBST QUOT,
-    ESCAPE DELIM,
-    ESCAPE DELIM       WORDSEP,
-    0,
-    ESCAPE DELIM       QUOT,
-    ESCAPE DELIM SUBST,
-    ESCAPE DELIM SUBST WORDSEP,
-    0,
-    ESCAPE DELIM SUBST QUOT
-
-#undef COMMON
+    ESCAPE,                            /* --- */
+    ESCAPE            WORDSEP,         /* SPLIT */
+    0,                                 /*         QUOT */
+    ESCAPE            QUOT,            /* SPLIT | QUOT */
+    ESCAPE      SUBST,                 /*                SUBST */
+    ESCAPE      SUBST WORDSEP,         /* SPLIT |        SUBST */
+    0,                                 /*         QUOT | SUBST */
+    ESCAPE      SUBST QUOT,            /* SPLIT | QUOT | SUBST */
+    ESCAPE DELIM,                      /*                        SUBEXPR */
+    ESCAPE DELIM       WORDSEP,                /* SPLIT |                SUBEXPR */
+    0,                                 /*         QUOT |         SUBEXPR */
+    ESCAPE DELIM       QUOT,           /* SPLIT | QUOT |         SUBEXPR */
+    ESCAPE DELIM SUBST,                        /*                SUBST | SUBEXPR */
+    ESCAPE DELIM SUBST WORDSEP,                /* SPLIT |        SUBST | SUBEXPR */
+    0,                                 /*         QUOT | SUBST | SUBEXPR */
+    ESCAPE DELIM SUBST QUOT            /* SPLIT | QUOT | SUBST | SUBEXPR */
+
+#undef ESCAPE
+#undef SUBST
 #undef WORDSEP
-#undef SQUOT
+#undef QUOT
 #undef DELIM
   };
 
@@ -1461,7 +1463,7 @@ static const char *subst(const char *p, const char *l,
 
       if (!(f&SF_SKIP)) {
 
-       /* If this is a double quote or backslash then check DFLT to see if
+       /* If this is a double quote or backslash then check QFILT to see if
         * it needs escaping.
         */
        if (qfilt && (*p == '"' || *p == '\\'))