From 539156430aea44c700e40f25557994ecddae6165 Mon Sep 17 00:00:00 2001
From: Stephen Dolan <mu@netsoc.tcd.ie>
Date: Sun, 16 Sep 2012 11:08:42 +0100
Subject: [PATCH] Builtin function 'length', for arrays/objects/strings.

---
 c/builtin.c | 15 +++++++++++++++
 c/testdata  |  3 +++
 2 files changed, 18 insertions(+)

diff --git a/c/builtin.c b/c/builtin.c
index 375e3252..39d3f24d 100644
--- a/c/builtin.c
+++ b/c/builtin.c
@@ -129,6 +129,20 @@ static void f_tonumber(jv input[], jv output[]) {
   }
 }
 
+static void f_length(jv input[], jv output[]) {
+  if (jv_get_kind(input[0]) == JV_KIND_ARRAY) {
+    output[0] = jv_number(jv_array_length(input[0]));
+  } else if (jv_get_kind(input[0]) == JV_KIND_OBJECT) {
+    output[0] = jv_number(jv_object_length(input[0]));
+  } else if (jv_get_kind(input[0]) == JV_KIND_STRING) {
+    output[0] = jv_number(jv_string_length(input[0]));
+  } else {
+    output[0] = jv_invalid_with_msg(jv_string_fmt("Cannot get the length of %s",
+                                                  jv_kind_name(jv_get_kind(input[0]))));
+    jv_free(input[0]);
+  }
+}
+
 struct cfunction function_list[] = {
   {f_true, "true", CALL_BUILTIN_1_1},
   {f_false, "false", CALL_BUILTIN_1_1},
@@ -139,5 +153,6 @@ struct cfunction function_list[] = {
   {f_divide, "_divide", CALL_BUILTIN_3_1},
   {f_tonumber, "tonumber", CALL_BUILTIN_1_1},
   {f_equal, "_equal", CALL_BUILTIN_3_1},
+  {f_length, "length", CALL_BUILTIN_1_1},
 };
 struct symbol_table builtins = {function_list, sizeof(function_list)/sizeof(function_list[0])};
diff --git a/c/testdata b/c/testdata
index a905d2af..f2eb32a2 100644
--- a/c/testdata
+++ b/c/testdata
@@ -203,6 +203,9 @@ null
 [false, false, false, false, false, false, false, true,  false]
 [false, false, false, false, false, false, false, false, true ]
 
+[.[] | length]
+[[], {}, [1,2], {"a":42}, "asdf"]
+[0, 0, 2, 1, 4]
 
 #
 # User-defined functions