Changeset 40652 for trunk/Ohana/src/opihi/lib.shell/expand_vars.c

Timestamp:

Mar 29, 2019, 5:05:27 AM (7 years ago)

Author:

eugene

Message:

allow nested variables in lists (e.g., $ref = foo, $foo:n = a, $$ref:n = a); add list -file option

File:

• trunk/Ohana/src/opihi/lib.shell/expand_vars.c (modified) (8 diffs)

trunk/Ohana/src/opihi/lib.shell/expand_vars.c

@@ -23 +23 @@
 
   /* look for form $a$b..$n and expand only the last ones */
+
+  // expand from line (L) into newline (N)
   for (L = line, N = newline; *L != 0; N++, L++) {  /* loop until end of line */
+
+    // look for end of line or start of variable ($)
     for (done = FALSE; !done;) {
       if (*L == 0) done = TRUE;
+
+      // look for the last $var
       if (*L == '$') {
         V1 = aftervar(L);
@@ -31 +37 @@
         if (V1 == NULL) done = TRUE;
       }
+
+      // copy into newline
       if (!done) { 
         *N = *L;
@@ -44 +52 @@
     }
 
+    // end of the line
     if (*L == 0) break;
 
@@ -50 +59 @@
     /* note: V1 points to a fraction of L, it does not need to be freed */
 
-    /* no variable name */
+    /* no variable name, e.g., word$ or $$.  keep the $ intact */
     if (V0 == NULL) {
       *N = *L;
@@ -62 +71 @@
     }
 
-    /* variable assignment (skip these variables) */
+    /* variable assignment ($ at start of the line) : skip these variables */
     if ((L == line) && (V1 != NULL)) {
       int isAssignment;
@@ -86 +95 @@
     }
 
+    // V0 is the name of a variable.  
+    // $tree_$branch_$twig should work (e.g,. $foo_bar_baz exists, $twig = baz, $foo_bar_$twig )
+    // $ref = name; echo $$ref:n word  need to expand $ref to get value of $name:n
+
+    // examples of valid nested variables, given $name = value, $ref = name, $name:n = 1, $name:0 = a, $i = 0
+    // $$ref -> value
+    // $$ref:n -> $name:n
+    // $$ref:$i -> $$ref:0 $name:9
+    
+    // is there a $ in the previous character?
+    // do not include ':' in the variable name
+    int isRef = FALSE;
+    if ((L != line) && (L[-1] == '$')) {
+      free (V0);
+      V0 = thisref(L);
+      isRef = TRUE;
+    }
+
+    // check for macro-arguments ($1, $2)
     found = TRUE;
     for (c = V0; isdigit(*c); c++); /* test if this is a macro argument variable (ie, $1.2) */
@@ -100 +128 @@
       }
     }
+
+    // we have something of the form $word, where V0 now is word.  expand it out:
 
     Val = get_variable_ptr (V0);
@@ -117 +147 @@
     N--; /* we overshoot on last loop */
 
-    /* skip past the variable in the source line */
+    /* skip past the variable (or reference) in the source line */
     /* L currently points at $ */
     L++;
     if (*L == '?') L++;  /* skip past ? in $?name */
 
-    while (ISVAR(*L)) L++;
+    if (isRef) {
+      while (ISREF(*L)) L++;
+    } else {
+      while (ISVAR(*L)) L++;
+    }
     L--; /* we overshoot */