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Port the BASIC interpreter from Go to C

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Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.

The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.

Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.

Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.

src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.

Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.

Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.

The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.

ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Andrew Kesterson
2026-07-30 23:53:56 -04:00
commit f8c15c2f2c
60 changed files with 10192 additions and 0 deletions
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245
tests/runtime_verbs.c Normal file
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/**
* @file runtime_verbs.c
* @brief Tests the verbs the golden corpus never reaches.
*
* LIST, DELETE, AUTO, INPUT, DLOAD, DSAVE, EXIT, STOP and the memory verbs are
* all real code with no `.bas`/`.txt` pair behind them, because the reference's
* own corpus never exercises them either. They are driven through a whole
* runtime here rather than unit-tested in pieces: most of them exist to mutate
* runtime state, and that is the thing worth asserting.
*/
#include <stdio.h>
#include <unistd.h>
#include "harness.h"
/* Run one line as though it had been typed at the REPL. */
static akerr_ErrorContext AKERR_NOIGNORE *run_line(const char *line)
{
PREPARE_ERROR(errctx);
akbasic_ASTLeaf *leaf = NULL;
akbasic_Value *out = NULL;
PASS(errctx, akbasic_environment_zero(HARNESS_RUNTIME.environment));
PASS(errctx, harness_parse(line, &leaf));
PASS(errctx, akbasic_runtime_evaluate(&HARNESS_RUNTIME, leaf, &out));
SUCCEED_RETURN(errctx);
}
/* Load a program into the source table the way RUNSTREAM would. */
static void load(const char *lines[], int count)
{
char scanned[AKBASIC_MAX_LINE_LENGTH];
int i = 0;
for ( i = 0; i < count; i++ ) {
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_OK(akbasic_scanner_scan(&HARNESS_RUNTIME, lines[i], scanned, sizeof(scanned)));
TEST_REQUIRE_OK(akbasic_runtime_store_line(&HARNESS_RUNTIME,
HARNESS_RUNTIME.environment->lineno, scanned));
}
}
static void clear_output(void)
{
memset(HARNESS_OUTPUT, 0, sizeof(HARNESS_OUTPUT));
rewind(HARNESS_OUT);
}
int main(void)
{
static const char *PROGRAM[] = {
"10 PRINT \"ONE\"",
"20 PRINT \"TWO\"",
"30 PRINT \"THREE\"",
};
char tmpname[] = "/tmp/akbasic_dsave_XXXXXX";
char buffer[256];
akbasic_Value *out = NULL;
FILE *saved = NULL;
int fd = -1;
TEST_REQUIRE_OK(harness_start("42\n"));
/* PRINT with no argument emits a bare newline. */
clear_output();
TEST_REQUIRE_OK(run_line("PRINT"));
TEST_REQUIRE_STR(HARNESS_OUTPUT, "\n");
/*
* LET does nothing; the assignment already happened during evaluation. A
* bare LET with no assignment after it is a parse error, in the reference
* too -- its parse path is just assignment(), which needs an expression.
*/
TEST_REQUIRE_OK(run_line("LET A# = 5"));
TEST_REQUIRE_ANY_ERROR(run_line("LET"));
/* LIST prints the program with its line numbers restored. */
load(PROGRAM, 3);
clear_output();
TEST_REQUIRE_OK(run_line("LIST"));
TEST_REQUIRE_STR(HARNESS_OUTPUT,
"10 PRINT \"ONE\"\n20 PRINT \"TWO\"\n30 PRINT \"THREE\"\n");
/* LIST n lists from n to the end. */
clear_output();
TEST_REQUIRE_OK(run_line("LIST 20"));
TEST_REQUIRE_STR(HARNESS_OUTPUT, "20 PRINT \"TWO\"\n30 PRINT \"THREE\"\n");
/* LIST -n lists from the start through n. */
clear_output();
TEST_REQUIRE_OK(run_line("LIST -20"));
TEST_REQUIRE_STR(HARNESS_OUTPUT, "10 PRINT \"ONE\"\n20 PRINT \"TWO\"\n");
/* LIST n-n lists an inclusive range. */
clear_output();
TEST_REQUIRE_OK(run_line("LIST 20-30"));
TEST_REQUIRE_STR(HARNESS_OUTPUT, "20 PRINT \"TWO\"\n30 PRINT \"THREE\"\n");
/* DSAVE writes the program out; DLOAD reads it back. */
fd = mkstemp(tmpname);
TEST_REQUIRE(fd >= 0, "could not create a temporary file");
if ( fd >= 0 ) {
close(fd);
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
snprintf(buffer, sizeof(buffer), "DSAVE \"%s\"", tmpname);
TEST_REQUIRE_OK(run_line(buffer));
saved = fopen(tmpname, "r");
TEST_REQUIRE(saved != NULL, "DSAVE produced no file");
if ( saved != NULL ) {
TEST_REQUIRE(fgets(buffer, sizeof(buffer), saved) != NULL, "DSAVE wrote nothing");
TEST_REQUIRE_STR(buffer, "10 PRINT \"ONE\"\n");
fclose(saved);
}
/* DELETE with no range clears the whole program. */
TEST_REQUIRE_OK(run_line("DELETE"));
clear_output();
TEST_REQUIRE_OK(run_line("LIST"));
TEST_REQUIRE_STR(HARNESS_OUTPUT, "");
/* DLOAD brings it back. */
snprintf(buffer, sizeof(buffer), "DLOAD \"%s\"", tmpname);
TEST_REQUIRE_OK(run_line(buffer));
clear_output();
TEST_REQUIRE_OK(run_line("LIST"));
TEST_REQUIRE_STR(HARNESS_OUTPUT,
"10 PRINT \"ONE\"\n20 PRINT \"TWO\"\n30 PRINT \"THREE\"\n");
remove(tmpname);
}
/* DELETE n-n removes an inclusive range. */
TEST_REQUIRE_OK(run_line("DELETE 20-30"));
clear_output();
TEST_REQUIRE_OK(run_line("LIST"));
TEST_REQUIRE_STR(HARNESS_OUTPUT, "10 PRINT \"ONE\"\n");
/* A missing file is an error, not a crash. */
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_ANY_ERROR(run_line("DLOAD \"/nonexistent/akbasic/nope.bas\""));
/* An empty filename is refused before it reaches aksl_fopen. */
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_STATUS(run_line("DLOAD \"\""), AKBASIC_ERR_VALUE);
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_STATUS(run_line("DLOAD 5"), AKBASIC_ERR_TYPE);
/* AUTO sets and clears the line-numbering increment. */
TEST_REQUIRE_OK(run_line("AUTO 10"));
TEST_REQUIRE_INT(HARNESS_RUNTIME.autoLineNumber, 10);
TEST_REQUIRE_OK(run_line("AUTO"));
TEST_REQUIRE_INT(HARNESS_RUNTIME.autoLineNumber, 0);
/* INPUT prompts and stores. The harness input stream holds "42". */
clear_output();
TEST_REQUIRE_OK(run_line("INPUT \"AGE? \" N#"));
TEST_REQUIRE_STR(HARNESS_OUTPUT, "AGE? ");
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
{
akbasic_ASTLeaf *leaf = NULL;
TEST_REQUIRE_OK(harness_parse("A# = N#", &leaf));
TEST_REQUIRE_OK(akbasic_runtime_evaluate(&HARNESS_RUNTIME, leaf, &out));
TEST_REQUIRE_INT(out->intval, 42);
}
/* Mode transitions. */
TEST_REQUIRE_OK(run_line("STOP"));
TEST_REQUIRE_INT(HARNESS_RUNTIME.mode, AKBASIC_MODE_REPL);
TEST_REQUIRE_OK(run_line("RUN"));
TEST_REQUIRE_INT(HARNESS_RUNTIME.mode, AKBASIC_MODE_RUN);
TEST_REQUIRE_INT(HARNESS_RUNTIME.environment->nextline, 0);
TEST_REQUIRE_OK(run_line("RUN 20"));
TEST_REQUIRE_INT(HARNESS_RUNTIME.environment->nextline, 20);
/*
* QUIT sets a mode. It must not call exit(): a host game decides what
* quitting means, and this test would not survive it doing otherwise.
*/
TEST_REQUIRE_OK(run_line("QUIT"));
TEST_REQUIRE_INT(HARNESS_RUNTIME.mode, AKBASIC_MODE_QUIT);
TEST_REQUIRE_OK(akbasic_runtime_set_mode(&HARNESS_RUNTIME, AKBASIC_MODE_RUN));
/* State errors: verbs used outside the structure they need. */
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_STATUS(run_line("RETURN"), AKBASIC_ERR_STATE);
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_STATUS(run_line("EXIT"), AKBASIC_ERR_STATE);
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_STATUS(run_line("NEXT I#"), AKBASIC_ERR_STATE);
/* GOTO and GOSUB want an integer. */
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_STATUS(run_line("GOTO \"nope\""), AKBASIC_ERR_TYPE);
/* GOTO sets the next line. */
TEST_REQUIRE_OK(run_line("GOTO 30"));
TEST_REQUIRE_INT(HARNESS_RUNTIME.environment->nextline, 30);
/* GOSUB pushes an environment; RETURN pops it and restores the line. */
{
akbasic_Environment *before = HARNESS_RUNTIME.environment;
TEST_REQUIRE_OK(akbasic_environment_zero(before));
before->lineno = 100;
TEST_REQUIRE_OK(run_line("GOSUB 500"));
TEST_REQUIRE(HARNESS_RUNTIME.environment != before, "GOSUB must push an environment");
TEST_REQUIRE_INT(HARNESS_RUNTIME.environment->nextline, 500);
TEST_REQUIRE_INT(HARNESS_RUNTIME.environment->gosubReturnLine, 101);
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_OK(run_line("RETURN"));
TEST_REQUIRE(HARNESS_RUNTIME.environment == before, "RETURN must pop back");
TEST_REQUIRE_INT(before->nextline, 101);
}
/* LABEL records the current line under a name. */
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
HARNESS_RUNTIME.environment->lineno = 70;
TEST_REQUIRE_OK(run_line("LABEL AGAIN"));
{
int64_t where = 0;
TEST_REQUIRE_OK(akbasic_environment_get_label(HARNESS_RUNTIME.environment, "AGAIN", &where));
TEST_REQUIRE_INT(where, 70);
}
/* POKE, PEEK and POINTER round-trip through real memory. */
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_OK(run_line("V# = 255"));
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_OK(run_line("P# = POINTER(V#)"));
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_OK(run_line("Q# = PEEK(P#)"));
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_OK(run_line("POKE P#, 127"));
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_OK(run_line("R# = POINTERVAR(V#)"));
/* PEEK through a null address is refused rather than segfaulting. */
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_OK(run_line("Z# = 0"));
TEST_REQUIRE_OK(akbasic_environment_zero(HARNESS_RUNTIME.environment));
TEST_REQUIRE_STATUS(run_line("Y# = PEEK(Z#)"), AKBASIC_ERR_VALUE);
harness_stop();
return akbasic_test_failures;
}