patch 9.0.0202: code and help for indexof() is not ideal

Problem:    Code and help for indexof() is not ideal.
Solution:   Refactor the code, improve the help. (Yegappan Lakshmanan,
            closes #10908)

runtime/doc/builtin.txt

@@ -4733,7 +4733,7 @@ indent({lnum})	The result is a Number, which is indent of line {lnum} in the
 
 index({object}, {expr} [, {start} [, {ic}]])			*index()*
 		Find {expr} in {object} and return its index.  See
-		|filterof()| for using a lambda to select the item.
+		|indexof()| for using a lambda to select the item.
 
 		If {object} is a |List| return the lowest index where the item
 		has a value equal to {expr}.  There is no automatic
@@ -4759,15 +4759,17 @@ index({object}, {expr} [, {start} [, {ic}]])			*index()*
 <		Can also be used as a |method|: >
 			GetObject()->index(what)
 
-indexof({object}, {expr} [, {opt}])			*indexof()*
+indexof({object}, {expr} [, {opts}])			*indexof()*
-		{object} must be a |List| or a |Blob|.
+		Returns the index of an item in {object} where {expr} is
+		v:true.  {object} must be a |List| or a |Blob|.
+
 		If {object} is a |List|, evaluate {expr} for each item in the
-		List until the expression returns v:true and return the index
+		List until the expression is v:true and return the index of
-		of this item.
+		this item.
 
 		If {object} is a |Blob| evaluate {expr} for each byte in the
-		Blob until the expression returns v:true and return the index
+		Blob until the expression is v:true and return the index of
-		of this byte.
+		this byte.
 
 		{expr} must be a |string| or |Funcref|.
 
@@ -4783,16 +4785,17 @@ indexof({object}, {expr} [, {opt}])			*indexof()*
 		The function must return |TRUE| if the item is found and the
 		search should stop.
 
-		The optional argument {opt} is a Dict and supports the
+		The optional argument {opts} is a Dict and supports the
 		following items:
-		    start	start evaluating {expr} at the item with index
+		    startidx	start evaluating {expr} at the item with this
-				{start} (may be negative for an item relative
+				index; may be negative for an item relative to
-				to the end).
+				the end
 		Returns -1 when {expr} evaluates to v:false for all the items.
 		Example: >
-			:let l = [#{n: 10}, #{n: 20}, #{n: 30]]
+			:let l = [#{n: 10}, #{n: 20}, #{n: 30}]
-			:let idx = indexof(l, "v:val.n == 20")
+			:echo indexof(l, "v:val.n == 20")
-			:let idx = indexof(l, {i, v -> v.n == 30})
+			:echo indexof(l, {i, v -> v.n == 30})
+			:echo indexof(l, "v:val.n == 20", #{startidx: 1})
 
 <		Can also be used as a |method|: >
 			mylist->indexof(expr)

src/evalfunc.c

@@ -6818,17 +6818,90 @@ indexof_eval_expr(typval_T *expr)
     return error ? FALSE : found;
 }
 
+/*
+ * Evaluate 'expr' for each byte in the Blob 'b' starting with the byte at
+ * 'startidx' and return the index of the byte where 'expr' is TRUE.  Returns
+ * -1 if 'expr' doesn't evaluate to TRUE for any of the bytes.
+ */
+    static int
+indexof_blob(blob_T *b, long startidx, typval_T *expr)
+{
+    long	idx = 0;
+
+    if (b == NULL)
+	return -1;
+
+    if (startidx < 0)
+    {
+	// negative index: index from the last byte
+	startidx = blob_len(b) + startidx;
+	if (startidx < 0)
+	    startidx = 0;
+    }
+
+    set_vim_var_type(VV_KEY, VAR_NUMBER);
+    set_vim_var_type(VV_VAL, VAR_NUMBER);
+
+    for (idx = startidx; idx < blob_len(b); ++idx)
+    {
+	set_vim_var_nr(VV_KEY, idx);
+	set_vim_var_nr(VV_VAL, blob_get(b, idx));
+
+	if (indexof_eval_expr(expr))
+	    return idx;
+    }
+
+    return -1;
+}
+
+/*
+ * Evaluate 'expr' for each item in the List 'l' starting with the item at
+ * 'startidx' and return the index of the item where 'expr' is TRUE.  Returns
+ * -1 if 'expr' doesn't evaluate to TRUE for any of the items.
+ */
+    static int
+indexof_list(list_T *l, long startidx, typval_T *expr)
+{
+    listitem_T	*item;
+    long	idx = 0;
+
+    if (l == NULL)
+	return -1;
+
+    CHECK_LIST_MATERIALIZE(l);
+
+    if (startidx == 0)
+	item = l->lv_first;
+    else
+    {
+	// Start at specified item.  Use the cached index that list_find()
+	// sets, so that a negative number also works.
+	item = list_find(l, startidx);
+	if (item != NULL)
+	    idx = l->lv_u.mat.lv_idx;
+    }
+
+    set_vim_var_type(VV_KEY, VAR_NUMBER);
+
+    for ( ; item != NULL; item = item->li_next, ++idx)
+    {
+	set_vim_var_nr(VV_KEY, idx);
+	copy_tv(&item->li_tv, get_vim_var_tv(VV_VAL));
+
+	if (indexof_eval_expr(expr))
+	    return idx;
+    }
+
+    return -1;
+}
+
 /*
  * "indexof()" function
  */
     static void
 f_indexof(typval_T *argvars, typval_T *rettv)
 {
-    list_T	*l;
-    listitem_T	*item;
-    blob_T	*b;
     long	startidx = 0;
-    long	idx = 0;
     typval_T	save_val;
     typval_T	save_key;
     int		save_did_emsg;
@@ -6857,67 +6930,12 @@ f_indexof(typval_T *argvars, typval_T *rettv)
     did_emsg = FALSE;
 
     if (argvars[0].v_type == VAR_BLOB)
-    {
+	rettv->vval.v_number = indexof_blob(argvars[0].vval.v_blob, startidx,
-	b = argvars[0].vval.v_blob;
+								&argvars[1]);
-	if (b == NULL)
-	    goto theend;
-	if (startidx < 0)
-	{
-	    startidx = blob_len(b) + startidx;
-	    if (startidx < 0)
-		startidx = 0;
-	}
-
-	set_vim_var_type(VV_KEY, VAR_NUMBER);
-	set_vim_var_type(VV_VAL, VAR_NUMBER);
-
-	for (idx = startidx; idx < blob_len(b); ++idx)
-	{
-	    set_vim_var_nr(VV_KEY, idx);
-	    set_vim_var_nr(VV_VAL, blob_get(b, idx));
-
-	    if (indexof_eval_expr(&argvars[1]))
-	    {
-		rettv->vval.v_number = idx;
-		break;
-	    }
-	}
-    }
     else
-    {
+	rettv->vval.v_number = indexof_list(argvars[0].vval.v_list, startidx,
-	l = argvars[0].vval.v_list;
+								&argvars[1]);
-	if (l == NULL)
-	    goto theend;
 
-	CHECK_LIST_MATERIALIZE(l);
-
-	if (startidx == 0)
-	    item = l->lv_first;
-	else
-	{
-	    // Start at specified item.  Use the cached index that list_find()
-	    // sets, so that a negative number also works.
-	    item = list_find(l, startidx);
-	    if (item != NULL)
-		idx = l->lv_u.mat.lv_idx;
-	}
-
-	set_vim_var_type(VV_KEY, VAR_NUMBER);
-
-	for ( ; item != NULL; item = item->li_next, ++idx)
-	{
-	    set_vim_var_nr(VV_KEY, idx);
-	    copy_tv(&item->li_tv, get_vim_var_tv(VV_VAL));
-
-	    if (indexof_eval_expr(&argvars[1]))
-	    {
-		rettv->vval.v_number = idx;
-		break;
-	    }
-	}
-    }
-
-theend:
     restore_vimvar(VV_KEY, &save_key);
     restore_vimvar(VV_VAL, &save_val);
     did_emsg |= save_did_emsg;

src/testdir/test_vim9_builtin.vim

@@ -2067,10 +2067,17 @@ def Test_index()
 enddef
 
 def Test_indexof()
-  var l = [{color: 'red'}, {color: 'blue'}, {color: 'green'}]
+  var l = [{color: 'red'}, {color: 'blue'}, {color: 'green'}, {color: 'blue'}]
-  indexof(l, (i, v) => v.color == 'green')->assert_equal(2)
+  indexof(l, (i, v) => v.color == 'blue')->assert_equal(1)
+  indexof(l, (i, v) => v.color == 'blue', {startidx: 1})->assert_equal(1)
+  indexof(l, (i, v) => v.color == 'blue', {startidx: 2})->assert_equal(3)
   var b = 0zdeadbeef
   indexof(b, "v:val == 0xef")->assert_equal(3)
+
+  def TestIdx(k: number, v: dict<any>): bool
+    return v.color == 'blue'
+  enddef
+  indexof(l, TestIdx)->assert_equal(1)
 enddef
 
 def Test_input()

src/version.c

@@ -735,6 +735,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    202,
 /**/
     201,
 /**/