Filter: Implement for loops
For loops allow to iterate over elements in compound data like BGP paths or community lists. The syntax is: for [ <type> ] <variable> in <expr> do <command-body>
This commit is contained in:
Ondrej Zajicek (work)
Ondrej Zajicek
parent
1ac8e11bba
commit
cb339a3067
8 changed files with 254 additions and 8 deletions
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@ -1683,7 +1683,8 @@ prefix and an ASN as arguments.
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<sect>Control structures
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<label id="control-structures">
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<p>Filters support two control structures: conditions and case switches.
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<p>Filters support several control structures: conditions, for loops and case
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switches.
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<p>Syntax of a condition is: <cf>if <M>boolean expression</M> then <m/commandT/;
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else <m/commandF/;</cf> and you can use <cf>{ <m/command1/; <m/command2/;
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@ -1691,6 +1692,14 @@ else <m/commandF/;</cf> and you can use <cf>{ <m/command1/; <m/command2/;
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omitted. If the <cf><m>boolean expression</m></cf> is true, <m/commandT/ is
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executed, otherwise <m/commandF/ is executed.
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<p>For loops allow to iterate over elements in compound data like BGP paths or
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community lists. The syntax is: <cf>for [ <m/type/ ] <m/variable/ in <m/expr/
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do <m/command/;</cf> and you can also use compound command like in conditions.
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The expression is evaluated to a compound data, then for each element from such
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data the command is executed with the item assigned to the variable. A variable
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may be an existing one (when just name is used) or a locally defined (when type
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and name is used). In both cases, it must have the same type as elements.
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<p>The <cf>case</cf> is similar to case from Pascal. Syntax is <cf>case
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<m/expr/ { else: | <m/num_or_prefix [ .. num_or_prefix]/: <m/statement/ ; [
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... ] }</cf>. The expression after <cf>case</cf> can be of any type which can be
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@ -1703,16 +1712,21 @@ neither of the <cf/:/ clauses, the statements after <cf/else:/ are executed.
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<p>Here is example that uses <cf/if/ and <cf/case/ structures:
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<code>
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if 1234 = i then printn "."; else {
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print "not 1234";
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print "You need {} around multiple commands";
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}
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for int asn in bgp_path do {
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printn "ASN: ", asn;
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if asn < 65536 then print " (2B)"; else print " (4B)";
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}
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case arg1 {
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2: print "two"; print "I can do more commands without {}";
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3 .. 5: print "three to five";
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else: print "something else";
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}
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if 1234 = i then printn "."; else {
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print "not 1234";
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print "You need {} around multiple commands";
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}
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</code>
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@ -307,6 +307,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
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INT, BOOL, IP, TYPE, PREFIX, RD, PAIR, QUAD, EC, LC,
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SET, STRING, BGPMASK, BGPPATH, CLIST, ECLIST, LCLIST,
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IF, THEN, ELSE, CASE,
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FOR, IN, DO,
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TRUE, FALSE, RT, RO, UNKNOWN, GENERIC,
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FROM, GW, NET, MASK, PROTO, SOURCE, SCOPE, DEST, IFNAME, IFINDEX, WEIGHT, GW_MPLS,
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PREFERENCE,
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@ -342,6 +343,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
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%type <v> set_atom switch_atom fipa
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%type <px> fprefix
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%type <t> get_cf_position
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%type <s> for_var
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CF_GRAMMAR
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@ -899,6 +901,11 @@ var:
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$$ = f_new_inst(FI_VAR_INIT, $3, sym);
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}
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for_var:
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type symbol { $$ = cf_define_symbol($2, SYM_VARIABLE | $1, offset, f_new_var(sym_->scope)); }
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| CF_SYM_KNOWN { $$ = $1; cf_assert_symbol($1, SYM_VARIABLE); }
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;
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cmd:
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'{' cmds_scoped '}' {
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$$ = $2;
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@ -909,6 +916,18 @@ cmd:
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| IF term THEN cmd ELSE cmd {
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$$ = f_new_inst(FI_CONDITION, $2, $4, $6);
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}
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| FOR {
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/* Reserve space for walk data on stack */
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cf_push_scope(NULL);
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conf_this_scope->slots += 2;
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} for_var IN
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/* Parse term in the parent scope */
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{ conf_this_scope->active = 0; } term { conf_this_scope->active = 1; }
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DO cmd {
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cf_pop_scope();
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$$ = f_new_inst(FI_FOR_INIT, $6, $3);
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$$->next = f_new_inst(FI_FOR_NEXT, $3, $9);
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}
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| CF_SYM_KNOWN '=' term ';' {
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switch ($1->class) {
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case SYM_VARIABLE_RANGE:
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@ -72,6 +72,7 @@ enum f_type
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f_type_element_type(enum f_type t)
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{
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switch(t) {
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case T_PATH: return T_INT;
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case T_CLIST: return T_PAIR;
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case T_ECLIST: return T_EC;
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case T_LCLIST: return T_LC;
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@ -87,6 +87,11 @@
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* m4_dnl RESULT_VOID; return undef
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* m4_dnl }
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*
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* Note that runtime arguments m4_dnl (ARG*, VARARG) must be defined before
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* parse-time arguments m4_dnl (LINE, SYMBOL, ...). During linearization,
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* first ones move position in f_line by linearizing arguments first, while
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* second ones store data to the current position.
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*
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* Also note that the { ... } blocks are not respected by M4 at all.
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* If you get weird unmatched-brace-pair errors, check what it generated and why.
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* What is really considered as one instruction is not the { ... } block
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@ -543,6 +548,94 @@
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RESULT_VAL(val);
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}
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INST(FI_FOR_INIT, 1, 0) {
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NEVER_CONSTANT;
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ARG_ANY(1);
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SYMBOL;
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FID_NEW_BODY()
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ASSERT((sym->class & ~0xff) == SYM_VARIABLE);
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/* Static type check */
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if (f1->type)
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{
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enum f_type t_var = (sym->class & 0xff);
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enum f_type t_arg = f_type_element_type(f1->type);
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if (!t_arg)
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cf_error("Value of expression in FOR must be iterable, got %s",
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f_type_name(f1->type));
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if (t_var != t_arg)
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cf_error("Loop variable '%s' in FOR must be %s, is %s",
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sym->name, f_type_name(t_arg), f_type_name(t_var));
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}
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FID_INTERPRET_BODY()
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/* Dynamic type check */
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if ((sym->class & 0xff) != f_type_element_type(v1.type))
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runtime("Mismatched argument and variable type");
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/* Setup the index */
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v2 = (struct f_val) { .type = T_INT, .val.i = 0 };
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/* Keep v1 and v2 on the stack */
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fstk->vcnt += 2;
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}
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INST(FI_FOR_NEXT, 2, 0) {
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NEVER_CONSTANT;
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SYMBOL;
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/* Type checks are done in FI_FOR_INIT */
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/* Loop variable */
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struct f_val *var = &fstk->vstk[curline.vbase + sym->offset];
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int step = 0;
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switch(v1.type)
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{
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case T_PATH:
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var->type = T_INT;
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step = as_path_walk(v1.val.ad, &v2.val.i, &var->val.i);
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break;
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case T_CLIST:
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var->type = T_PAIR;
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step = int_set_walk(v1.val.ad, &v2.val.i, &var->val.i);
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break;
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case T_ECLIST:
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var->type = T_EC;
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step = ec_set_walk(v1.val.ad, &v2.val.i, &var->val.ec);
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break;
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case T_LCLIST:
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var->type = T_LC;
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step = lc_set_walk(v1.val.ad, &v2.val.i, &var->val.lc);
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break;
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default:
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runtime( "Clist or lclist expected" );
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}
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if (step)
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{
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/* Keep v1 and v2 on the stack */
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fstk->vcnt += 2;
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/* Repeat this instruction */
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curline.pos--;
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/* Execute the loop body */
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LINE(1, 0);
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/* Space for loop variable, may be unused */
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fstk->vcnt += 1;
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}
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else
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var->type = T_VOID;
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}
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INST(FI_CONDITION, 1, 0) {
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ARG(1, T_BOOL);
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if (v1.val.i)
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@ -758,6 +758,15 @@ int set set12;
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bt_assert(delete(p2, [4..5]) = prepend(prepend(prepend(prepend(+empty+, 3), 3), 2), 1));
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bt_assert(format([= 1 2+ 3 =]) = "[= 1 2 + 3 =]");
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# iteration over path
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int x = 0;
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int y = 0;
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for int i in p2 do {
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x = x + i;
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y = y + x;
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}
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bt_assert(x = 18 && y = 50);
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}
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bt_test_suite(t_path, "Testing paths");
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@ -884,6 +893,12 @@ clist r;
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bt_assert(format(r) = "(clist (2,1) (1,3) (2,2) (3,1) (2,3))");
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bt_assert(r.min = (1,3));
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bt_assert(r.max = (3,1));
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# iteration over clist
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int x = 0;
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for pair c in r do
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x = x + c.asn * c.asn * c.data;
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bt_assert(x = 36);
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}
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bt_test_suite(t_clist, "Testing lists of communities");
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@ -999,6 +1014,13 @@ eclist r;
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bt_assert(format(r) = "(eclist (rt, 2, 1) (rt, 1, 3) (rt, 2, 2) (rt, 3, 1) (rt, 2, 3))");
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bt_assert(r.min = (rt, 1, 3));
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bt_assert(r.max = (rt, 3, 1));
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# iteration over eclist
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int x = 0;
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for ec c in r do
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if c > (rt, 2, 0) && c < (rt, 3, 0) then
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x = x + 1;
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bt_assert(x = 3);
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}
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bt_test_suite(t_eclist, "Testing lists of extended communities");
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@ -1117,6 +1139,19 @@ lclist r;
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bt_assert(format(r) = "(lclist (2, 3, 3) (1, 2, 3) (2, 3, 1) (3, 1, 2) (2, 1, 3))");
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bt_assert(r.min = (1, 2, 3));
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bt_assert(r.max = (3, 1, 2));
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# iteration over lclist
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int x = 0;
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int y = 0;
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lc mx = (0, 0, 0);
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for lc c in r do {
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int asn2 = c.asn * c.asn;
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x = x + asn2 * c.data1;
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y = y + asn2 * c.data2;
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if c > mx then mx = c;
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}
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bt_assert(x = 39 && y = 49);
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bt_assert(mx = r.max);
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}
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bt_test_suite(t_lclist, "Testing lists of large communities");
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@ -1580,13 +1615,16 @@ filter vpn_filter
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bt_assert(net.type != NET_IP6);
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bt_assert(net.rd = 0:1:2);
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bool b = false;
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case (net.type) {
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NET_IP4: print "IPV4";
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NET_IP6: print "IPV6";
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else: b = true;
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}
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bt_assert(b);
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bt_check_assign(from, 10.20.30.40);
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bt_check_assign(gw, 55.55.55.44);
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# bt_check_assign(gw, 55.55.55.44);
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bgp_community.add((3,5));
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bgp_ext_community.add((ro, 135, 999));
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@ -669,6 +669,35 @@ as_path_filter(struct linpool *pool, const struct adata *path, const struct f_va
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return res;
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}
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int
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as_path_walk(const struct adata *path, uint *pos, uint *val)
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{
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if (!path)
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return 0;
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const u8 *p = path->data;
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const u8 *q = p + path->length;
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uint n, x = *pos;
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while (p < q)
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{
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n = p[1];
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p += 2;
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if (x < n)
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{
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*val = get_as(p + x * BS);
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*pos += 1;
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return 1;
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}
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p += n * BS;
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x -= n;
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}
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return 0;
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}
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struct pm_pos
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{
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48
nest/a-set.c
48
nest/a-set.c
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@ -693,3 +693,51 @@ lc_set_max(const struct adata *list, lcomm *val)
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*val = (lcomm) { res[0], res[1], res[2] };
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return 1;
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}
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int
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int_set_walk(const struct adata *list, uint *pos, uint *val)
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{
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if (!list)
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return 0;
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if (*pos >= (uint) int_set_get_size(list))
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return 0;
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u32 *res = int_set_get_data(list) + *pos;
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*val = *res;
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*pos += 1;
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return 1;
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}
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int
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ec_set_walk(const struct adata *list, uint *pos, u64 *val)
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{
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if (!list)
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return 0;
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if (*pos >= (uint) int_set_get_size(list))
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return 0;
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u32 *res = int_set_get_data(list) + *pos;
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*val = ec_generic(res[0], res[1]);
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*pos += 2;
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return 1;
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}
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int
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lc_set_walk(const struct adata *list, uint *pos, lcomm *val)
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{
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if (!list)
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return 0;
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if (*pos >= (uint) int_set_get_size(list))
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return 0;
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u32 *res = int_set_get_data(list) + *pos;
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*val = (lcomm) { res[0], res[1], res[2] };
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*pos += 3;
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return 1;
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}
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@ -51,6 +51,7 @@ u32 as_path_get_last_nonaggregated(const struct adata *path);
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int as_path_contains(const struct adata *path, u32 as, int min);
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int as_path_match_set(const struct adata *path, const struct f_tree *set);
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const struct adata *as_path_filter(struct linpool *pool, const struct adata *path, const struct f_val *set, int pos);
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int as_path_walk(const struct adata *path, uint *pos, uint *val);
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static inline struct adata *as_path_prepend(struct linpool *pool, const struct adata *path, u32 as)
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{ return as_path_prepend2(pool, path, AS_PATH_SEQUENCE, as); }
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@ -225,6 +226,9 @@ int lc_set_min(const struct adata *list, lcomm *val);
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int int_set_max(const struct adata *list, u32 *val);
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int ec_set_max(const struct adata *list, u64 *val);
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int lc_set_max(const struct adata *list, lcomm *val);
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int int_set_walk(const struct adata *list, uint *pos, u32 *val);
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int ec_set_walk(const struct adata *list, uint *pos, u64 *val);
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int lc_set_walk(const struct adata *list, uint *pos, lcomm *val);
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void ec_set_sort_x(struct adata *set); /* Sort in place */
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