Filter: Implement mixed declarations of local variables
Allow variable declarations mixed with code, also in nested blocks with
proper scoping, and with variable initializers. E.g:
function fn(int a)
{
int b;
int c = 10;
if a > 20 then
{
b = 30;
int d = c * 2;
print a, b, c, d;
}
string s = "Hello";
}
This commit is contained in:
Ondrej Zajicek (work)
Ondrej Zajicek
parent
a2527ee53d
commit
1ac8e11bba
4 changed files with 116 additions and 37 deletions
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@ -1260,8 +1260,8 @@ this:
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<code>
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filter not_too_far
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int var;
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{
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int var;
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if defined( rip_metric ) then
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var = rip_metric;
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else {
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@ -1290,9 +1290,9 @@ local variables. Recursion is not allowed. Function definitions look like this:
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<code>
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function name ()
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int local_variable;
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{
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local_variable = 5;
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int local_variable;
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int another_variable = 5;
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}
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function with_parameters (int parameter)
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@ -1301,16 +1301,19 @@ function with_parameters (int parameter)
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}
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</code>
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<p>Unlike in C, variables are declared after the <cf/function/ line, but before
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the first <cf/{/. You can't declare variables in nested blocks. Functions are
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called like in C: <cf>name(); with_parameters(5);</cf>. Function may return
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values using the <cf>return <m/[expr]/</cf> command. Returning a value exits
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from current function (this is similar to C).
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<p>Like in C programming language, variables are declared inside function body,
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either at the beginning, or mixed with other statements. Declarations may
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contain initialization. You can also declare variables in nested blocks, such
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variables have scope restricted to such block. There is a deprecated syntax to
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declare variables after the <cf/function/ line, but before the first <cf/{/.
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Functions are called like in C: <cf>name(); with_parameters(5);</cf>. Function
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may return values using the <cf>return <m/[expr]/</cf> command. Returning a
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value exits from current function (this is similar to C).
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<p>Filters are defined in a way similar to functions except they can't have
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<p>Filters are defined in a way similar to functions except they cannot have
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explicit parameters. They get a route table entry as an implicit parameter, it
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is also passed automatically to any functions called. The filter must terminate
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with either <cf/accept/ or <cf/reject/ statement. If there's a runtime error in
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with either <cf/accept/ or <cf/reject/ statement. If there is a runtime error in
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filter, the route is rejected.
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<p>A nice trick to debug filters is to use <cf>show route filter <m/name/</cf>
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@ -22,6 +22,36 @@ static inline u32 pair_b(u32 p) { return p & 0xFFFF; }
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#define f_generate_complex(fi_code, da, arg) \
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f_new_inst(FI_EA_SET, f_new_inst(fi_code, f_new_inst(FI_EA_GET, da), arg), da)
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static int
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f_new_var(struct sym_scope *s)
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{
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/*
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* - A variable is an offset on vstack from vbase.
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* - Vbase is set on filter start / function call.
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* - Scopes contain anonymous scopes (blocks) inside filter/function scope
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* - Each scope knows number of vars in that scope
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* - Offset is therefore a sum of 'slots' up to named scope
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* - New variables are added on top of vstk, so intermediate values cannot
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* be there during FI_VAR_INIT. I.e. no 'var' inside 'term'.
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* - Also, each f_line must always have its scope, otherwise a variable may
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* be defined but not initialized if relevant f_line is not executed.
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*/
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int offset = s->slots++;
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while (!s->name)
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{
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s = s->next;
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ASSERT(s);
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offset += s->slots;
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}
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if (offset >= 0xff)
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cf_error("Too many variables, at most 255 allowed");
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return offset;
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}
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/*
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* Sets and their items are during parsing handled as lists, linked
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* through left ptr. The first item in a list also contains a pointer
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@ -296,7 +326,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
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%nonassoc ELSE
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%type <xp> cmds_int cmd_prep
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%type <x> term cmd cmds constant constructor print_list var_list function_call symbol_value bgp_path_expr bgp_path bgp_path_tail
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%type <x> term cmd cmd_var cmds cmds_scoped constant constructor print_list var var_init var_list function_call symbol_value bgp_path_expr bgp_path bgp_path_tail
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%type <fda> dynamic_attr
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%type <fsa> static_attr
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%type <f> filter where_filter
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@ -425,7 +455,7 @@ function_args:
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function_vars:
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/* EMPTY */ { $$ = 0; }
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| function_vars type symbol ';' {
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cf_define_symbol($3, SYM_VARIABLE | $2, offset, sym_->scope->slots++);
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cf_define_symbol($3, SYM_VARIABLE | $2, offset, f_new_var(sym_->scope));
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$$ = $1 + 1;
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}
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;
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@ -492,7 +522,11 @@ cmds: /* EMPTY */ { $$ = NULL; }
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| cmds_int { $$ = $1.begin; }
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;
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cmd_prep: cmd {
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cmds_scoped: { cf_push_soft_scope(); } cmds { cf_pop_soft_scope(); $$ = $2; } ;
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cmd_var: var | cmd ;
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cmd_prep: cmd_var {
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$$.begin = $$.end = $1;
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if ($1)
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while ($$.end->next)
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@ -639,7 +673,7 @@ fprefix_set:
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;
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switch_body: /* EMPTY */ { $$ = NULL; }
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| switch_body switch_items ':' cmds {
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| switch_body switch_items ':' cmds_scoped {
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/* Fill data fields */
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struct f_tree *t;
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struct f_line *line = f_linearize($4, 0);
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@ -647,7 +681,7 @@ switch_body: /* EMPTY */ { $$ = NULL; }
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t->data = line;
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$$ = f_merge_items($1, $2);
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}
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| switch_body ELSECOL cmds {
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| switch_body ELSECOL cmds_scoped {
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struct f_tree *t = f_new_tree();
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t->from.type = t->to.type = T_VOID;
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t->right = t;
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@ -854,8 +888,19 @@ print_list: /* EMPTY */ { $$ = NULL; }
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}
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;
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var_init:
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/* empty */ { $$ = f_new_inst(FI_CONSTANT, (struct f_val) { }); }
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| '=' term { $$ = $2; }
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;
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var:
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type symbol var_init ';' {
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struct symbol *sym = cf_define_symbol($2, SYM_VARIABLE | $1, offset, f_new_var(sym_->scope));
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$$ = f_new_inst(FI_VAR_INIT, $3, sym);
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}
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cmd:
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'{' cmds '}' {
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'{' cmds_scoped '}' {
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$$ = $2;
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}
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| IF term THEN cmd {
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@ -501,6 +501,18 @@
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RESULT(T_BOOL, i, ipa_is_ip4(v1.val.ip));
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}
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INST(FI_VAR_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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ARG_TYPE(1, sym->class & 0xff);
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/* New variable is always the last on stack */
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uint pos = curline.vbase + sym->offset;
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fstk->vstk[pos] = v1;
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fstk->vcnt = pos + 1;
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}
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/* Set to indirect value prepared in v1 */
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INST(FI_VAR_SET, 1, 0) {
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NEVER_CONSTANT;
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@ -44,9 +44,8 @@ bt_test_same(onef, twof, 0);
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*/
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function t_bool()
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bool b;
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{
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b = true;
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bool b = true;
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bt_assert(b);
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bt_assert(!!b);
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@ -82,12 +81,11 @@ define xyzzy = (120+10);
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define '1a-a1' = (xyzzy-100);
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function t_int()
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int i;
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{
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bt_assert(xyzzy = 130);
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bt_assert('1a-a1' = 30);
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i = four;
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int i = four;
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i = 12*100 + 60/2 + i;
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i = (i + 0);
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bt_assert(i = 1234);
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@ -128,9 +126,8 @@ define is2 = [(17+2), 17, 15, 11, 8, 5, 3, 2];
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define is3 = [5, 17, 2, 11, 8, 15, 3, 19];
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function t_int_set()
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int set is;
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{
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is = [];
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int set is = [];
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bt_assert(is = []);
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bt_assert(0 !~ is);
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@ -190,9 +187,8 @@ bt_test_suite(t_int_set, "Testing sets of integers");
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*/
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function t_string()
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string st;
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{
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st = "Hello";
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string st = "Hello";
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bt_assert(format(st) = "Hello");
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bt_assert(st ~ "Hell*");
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bt_assert(st ~ "?ello");
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@ -217,9 +213,8 @@ function 'mkpair-a'(int a)
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}
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function t_pair()
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pair pp;
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{
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pp = (1, 2);
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pair pp = (1, 2);
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bt_assert(format(pp) = "(1,2)");
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bt_assert((1,2) = pp);
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bt_assert((1,1+1) = pp);
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@ -240,11 +235,9 @@ bt_test_suite(t_pair, "Testing pairs");
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*/
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function t_pair_set()
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pair pp;
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pair set ps;
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{
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pp = (1, 2);
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ps = [];
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pair pp = (1, 2);
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pair set ps = [];
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bt_assert(pp !~ ps);
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ps = [(1,(one+one)), (3,4)..(4,8), (5,*), (6,3..6)];
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@ -1290,6 +1283,34 @@ function fifteen()
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return 15;
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}
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function local_vars(int j)
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{
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int k = 10;
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bt_assert(j = 5 && k = 10);
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{
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int j = 15;
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k = 20;
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bt_assert(j = 15 && k = 20);
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}
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bt_assert(j = 5 && k = 20);
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if j < 10 then
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{
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int j = 25;
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string k = "hello";
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bt_assert(j = 25 && k = "hello");
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}
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bt_assert(j = 5 && k = 20);
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int m = 100;
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{
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j = 35;
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int k = 40;
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bt_assert(j = 35 && k = 40 && m = 100);
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}
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bt_assert(j = 35 && k = 20 && m = 100);
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}
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function factorial(int x)
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{
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if x = 0 then return 0;
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@ -1312,21 +1333,18 @@ function hanoi_init(int a; int b)
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}
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function hanoi_solve(int n; bgppath h_src; bgppath h_dst; bgppath h_aux; bool x; bool y)
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bgppath tmp1;
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bgppath tmp2;
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int v;
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{
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# x -> return src or dst
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# y -> print state
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if n = 0 then { if x then return h_src; else return h_dst; }
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tmp1 = hanoi_solve(n - 1, h_src, h_aux, h_dst, true, y);
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tmp2 = hanoi_solve(n - 1, h_src, h_aux, h_dst, false, false);
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bgppath tmp1 = hanoi_solve(n - 1, h_src, h_aux, h_dst, true, y);
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bgppath tmp2 = hanoi_solve(n - 1, h_src, h_aux, h_dst, false, false);
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h_src = tmp1;
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h_aux = tmp2;
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v = h_src.first;
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int v = h_src.first;
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# bt_assert(h_dst = +empty+ || v < h_dst.first);
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h_src = delete(h_src, v);
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h_dst = prepend(h_dst, v);
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@ -1355,6 +1373,7 @@ bgppath h_src;
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bt_assert(callme(4, 4) = 16);
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bt_assert(callme(7, 2) = 14);
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bt_assert(callmeagain(1, 2, 3) = 6);
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local_vars(5);
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bt_assert(factorial(5) = 120);
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bt_assert(factorial(10) = 3628800);
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