Add break builtin for foreach

builtin.c

@@ -902,6 +902,7 @@ static block bind_bytecoded_builtins(block b) {
 #define LIBM_DD(name) "def " #name ": _" #name ";",
 
 static const char* const jq_builtins[] = {
+  "def break: error(\"break\");",
   "def map(f): [.[] | f];",
   "def select(f): if f then . else empty end;",
   "def sort(f): _sort_by_impl(map([f]));",

compile.c

@@ -406,7 +406,10 @@ block gen_foreach(const char* varname, block source, block init, block update, b
                         // it, so we backtrack.
                         gen_op_simple(BACKTRACK));
   inst_set_target(output, foreach);
-  return foreach;
+  block handler = gen_cond(gen_call("_equal", BLOCK(gen_lambda(gen_const(jv_string("break"))), gen_lambda(gen_noop()))),
+                           gen_op_simple(BACKTRACK),
+                           gen_call("break", gen_noop()));
+  return gen_try(foreach, handler);
 }
 
 block gen_definedor(block a, block b) {

docs/content/3.manual/manual.yml

@@ -1844,8 +1844,7 @@ sections:
           This is mostly useful only for constructing `reduce`- and
           `limit`-like functions.  But it is much more general, as it
           allows for partial reductions (see the example below), as well
-          as breaking out of the "loop" with `empty`, or even `error(x)`
-          if there's a try/catch around the foreach.
+          as breaking out of the "loop" with `break`.
 
         examples:
           - program: '[foreach .[] as $item

tests/all.test

@@ -226,7 +226,7 @@ null
 1
 [1,2,4,8,16,32,64]
 
-[foreach .[] as $item ([3, null]; if .[0] < 1 then empty else [.[0] -1, $item] end; .[1])]
+[foreach .[] as $item ([3, null]; if .[0] < 1 then break else [.[0] -1, $item] end; .[1])]
 [11,22,33,44,55,66,77,88,99]
 [11,22,33]