Add label $name | EXP; fix break

This is to fix the problem where `break` is dynamic, not lexical.

With this it should be possible to do this sort of thing:

    label $break | inputs | if ... then $break|error else . end

This is a backwards-incompatible change for master, but the previous
`break` hadn't shipped yet.

Still needed:

 - testing

parser.y

@@ -70,6 +70,10 @@ struct lexer_param;
 %token OR "or"
 %token TRY "try"
 %token CATCH "catch"
+%token LABEL "label"
+%token BREAK "break"
+%token BREAK2 "break2"
+%token BREAK3 "break3"
 %token SETPIPE "|="
 %token SETPLUS "+="
 %token SETMINUS "-="
@@ -149,6 +153,8 @@ int yylex(YYSTYPE* yylval, YYLTYPE* yylloc, block* answer, int* errors,
   return tok;
 }
 
+static unsigned int next_label = 0;
+
 static block gen_dictpair(block k, block v) {
   return BLOCK(gen_subexp(k), gen_subexp(v), gen_op_simple(INSERT));
 }
@@ -335,7 +341,7 @@ Term "as" '$' IDENT '|' Exp {
 
 "try" Exp "catch" Exp {
   //$$ = BLOCK(gen_op_target(FORK_OPT, $2), $2, $4);
-  $$ = gen_try($2, $4);
+  $$ = gen_try($2, gen_try_handler($4));
 } |
 "try" Exp {
   //$$ = BLOCK(gen_op_target(FORK_OPT, $2), $2, gen_op_simple(BACKTRACK));
@@ -346,6 +352,19 @@ Term "as" '$' IDENT '|' Exp {
   $$ = $2;
 } |
 
+"label" '|' Exp {
+  jv v = jv_string_fmt("*anonlabel%u", next_label++);
+  $$ = gen_location(@$, locations, gen_label(jv_string_value(v), $3));
+  jv_free(v);
+} |
+
+"label" '$' IDENT '|' Exp {
+  jv v = jv_string_fmt("*label-%s", jv_string_value($3));
+  $$ = gen_location(@$, locations, gen_label(jv_string_value(v), $5));
+  jv_free($3);
+  jv_free(v);
+} |
+
 // This rule conflicts with all the other rules using the '?' operator.
 // It doesn't matter which bison prefers: all of them result in the same
 // syntax and semantics, but the more specific rules optimize better
@@ -570,6 +589,29 @@ Term:
 REC {
   $$ = gen_call("recurse", gen_noop());
 } |
+BREAK {
+  $$ = gen_location(@$, locations,
+                    BLOCK(gen_op_unbound(LOADV, "*1"),  // impossible symbol
+                    gen_call("error", gen_noop())));
+} |
+BREAK2 {
+  $$ = gen_location(@$, locations,
+                    BLOCK(gen_op_unbound(LOADV, "*2"),  // impossible symbol
+                    gen_call("error", gen_noop())));
+} |
+BREAK3 {
+  $$ = gen_location(@$, locations,
+                    BLOCK(gen_op_unbound(LOADV, "*3"),  // impossible symbol
+                    gen_call("error", gen_noop())));
+} |
+BREAK '$' IDENT {
+  jv v = jv_string_fmt("*label-%s", jv_string_value($3));     // impossible symbol
+  $$ = gen_location(@$, locations,
+                    BLOCK(gen_op_unbound(LOADV, jv_string_value(v)),
+                    gen_call("error", gen_noop())));
+  jv_free(v);
+  jv_free($3);
+} |
 Term FIELD '?' {
   $$ = gen_index_opt($1, gen_const($2));
 } |