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Do not automatically execute bl:mp programs.
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With the addition of ! giving full control over execution order to
the programmer, there is no longer a need for exeuction to be a
built-in step in interpreting a bl:mp program. Now, the semantics of
a bl:mp program are defined as the semantics of parsing the program,
and the interpreter (in non-interactive) mode no longer executes the
parsed expression.

The std prelude is modified such that if it is prepended to a file,
it will automatically execute the contents of that file when it is
parsed. The interpreter is extended with a --preload option to prepend
files in this way, and the std prelude is implicitly prepended if
--core is not passed.

This is the first part of the final step towards #14 (the other part
being the analagous change for the test runner).
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@jbearer
jbearer committed Oct 11, 2021
1 parent 0ebfe92 commit b4e0b5e
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Showing 10 changed files with 492 additions and 131 deletions.
179 changes: 164 additions & 15 deletions blimp/src/blimp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -60,7 +60,18 @@ static void PrintUsage(FILE *f, int argc, char *const *argv)
fprintf(f, " in the formal semantics.\n");
fprintf(f, " * compile: print the compiled bytecode for an input\n");
fprintf(f, " expression\n");
fprintf(f, " The default is `eval'.\n");
fprintf(f, " The default is `eval' for interactive mode, `parse' for\n");
fprintf(f, " non-interactive mode.\n");
fprintf(f, "\n");
fprintf(f, " -I, --import-path DIR\n");
fprintf(f, " Search for imported modules in DIR. Multiple directories\n");
fprintf(f, " may be given by passing this option more than once.\n");
fprintf(f, "\n");
fprintf(f, " -l, --preload MODULE\n");
fprintf(f, " Prepend the given module to the input file. MOD will be\n");
fprintf(f, " searched in the import path, using the same search\n");
fprintf(f, " procedure as `import MOD'. More than one preload module\n");
fprintf(f, " may be given by passing this option more than once.\n");
fprintf(f, "\n");
fprintf(f, " --history-file FILE\n");
fprintf(f, " Load and save interactive history to and from FILE.\n");
Expand All @@ -83,6 +94,59 @@ static void PrintUsage(FILE *f, int argc, char *const *argv)
fprintf(f, "%s\n", BLIMP_OPTIONS_USAGE);
}

static BlimpStatus PreloadStream(
Blimp *blimp, const Options *options, BlimpStream **stream)
{
*stream = NULL;
for (size_t i = 0; i < options->prepend_len; ++i) {
// Locate the preload module in the module search path.
const char *preload_path;
BlimpModuleType type = BLIMP_MODULE_TEXT;
if (BlimpModule_Search(
blimp,
options->prepend[i],
options->import_path,
&type,
&preload_path
) != BLIMP_OK)
{
if (*stream != NULL) {
BlimpStream_Delete(*stream);
}
return Blimp_Reraise(blimp);
}

// Open a stream for the preload module
BlimpStream *file_stream;
if (Blimp_FileStream(blimp, preload_path, &file_stream)
!= BLIMP_OK)
{
free((void *)preload_path);
if (*stream != NULL) {
BlimpStream_Delete(*stream);
}
return Blimp_Reraise(blimp);
}
free((void *)preload_path);

// Append the new preload stream to the end of the stream we've already
// built up.
if (*stream == NULL) {
*stream = file_stream;
} else {
if (Blimp_ConcatStreams(blimp, *stream, file_stream, stream)
!= BLIMP_OK)
{
BlimpStream_Delete(*stream);
BlimpStream_Delete(file_stream);
return Blimp_Reraise(blimp);
}
}
}

return BLIMP_OK;
}

static bool IsRenderableStandardInstance(Blimp *blimp, BlimpObject *obj)
{
// Try to determine if the object is a standard instance of a class which
Expand Down Expand Up @@ -284,10 +348,26 @@ static BlimpStatus DoAction(
{
BlimpStatus status = BLIMP_OK;

Action action = options->action;
if (action == ACTION_DEFAULT) {
if (options->interactive) {
// In interactive mode, each input expression is evaluated
// automatically, as if it had been prefixed with !. Fall
// through to the ACTION_EVAL case.
action = ACTION_EVAL;
} else {
// In non-interactive mode, evaluation _is_ parsing, because the
// strict semantics of bl:mp state that the behavior of a
// program is simply the side-effects of parsing that program.
// `expr` is already parsed, so we have nothing left to do.
return BLIMP_OK;
}
}

Blimp_HandleSignal(blimp, BLIMP_INTERRUPT_SIGNAL, InterruptBlimp, db);
PushInterruptHandler(InterruptAction, blimp);

switch (options->action) {
switch (action) {
case ACTION_EVAL: {
BlimpObject *result;
if ((status = Blimp_Eval(
Expand Down Expand Up @@ -340,6 +420,32 @@ static BlimpStatus DoAction(

static int ReplMain(Blimp *blimp, const Options *options)
{
// Create an input stream for the parser which yields the contents of
// each preload file.
BlimpStream *stream;
if (PreloadStream(blimp, options, &stream) != BLIMP_OK) {
Blimp_DumpLastError(blimp, stderr);
return 1;
}

if (stream != NULL) {
// Execute the preloaded files.
BlimpParseTree tree;
if (Blimp_Parse(blimp, stream, &tree) != BLIMP_OK) {
Blimp_DumpLastError(blimp, stderr);
return 1;
}
BlimpExpr *expr;
if (BlimpParseTree_Eval(blimp, &tree, &expr) != BLIMP_OK) {
BlimpParseTree_Destroy(&tree);
Blimp_DumpLastError(blimp, stderr);
return 1;
}
BlimpParseTree_Destroy(&tree);
Blimp_FreeExpr(expr);
}

// Initialize the REPL.
Readline_Init(options);
PrintVersion(stdout);
InitCommands(blimp);
Expand All @@ -349,7 +455,7 @@ static int ReplMain(Blimp *blimp, const Options *options)
Debugger_Init(&db);
InitDebuggerCommands(blimp, &db);

Expr *expr;
BlimpExpr *expr;
while ((expr = Readline_ReadExpr(blimp, "bl:mp> ", false)) != NULL) {
if (DoAction(blimp, expr, options, &db) != BLIMP_OK) {
Blimp_DumpLastError(blimp, stdout);
Expand All @@ -374,6 +480,35 @@ static int ReplMain(Blimp *blimp, const Options *options)

static int EvalMain(Blimp *blimp, const char *path, const Options *options)
{
// Create an input stream for the parser which first yields the contents of
// each preload file and then the contents of `path`.
BlimpStream *stream;
if (PreloadStream(blimp, options, &stream) != BLIMP_OK) {
Blimp_DumpLastError(blimp, stderr);
return 1;
}
{
// Open a stream for the input file.
BlimpStream *file_stream;
if (Blimp_FileStream(blimp, path, &file_stream) != BLIMP_OK) {
if (stream != NULL) {
BlimpStream_Delete(stream);
}
Blimp_DumpLastError(blimp, stderr);
return 1;
}

// Append the stream to the end of the stream with the preload files.
if (Blimp_ConcatStreams(blimp, stream, file_stream, &stream)
!= BLIMP_OK)
{
BlimpStream_Delete(stream);
BlimpStream_Delete(file_stream);
Blimp_DumpLastError(blimp, stderr);
return 1;
}
}

Debugger db;
if (options->debug) {
Debugger_Init(&db);
Expand All @@ -399,7 +534,7 @@ static int EvalMain(Blimp *blimp, const char *path, const Options *options)
);
PushInterruptHandler(InterruptAction, blimp);
BlimpParseTree tree;
if (Blimp_ParseFile(blimp, path, &tree) != BLIMP_OK) {
if (Blimp_Parse(blimp, stream, &tree) != BLIMP_OK) {
Blimp_DumpLastError(blimp, stderr);
if (options->debug) {
Debugger_Detach(&db);
Expand Down Expand Up @@ -438,6 +573,7 @@ typedef enum {
FLAG_BLIMP_OPTION = 'f',
FLAG_OPTIMIZE = 'O',
FLAG_IMPORT_PATH = 'I',
FLAG_PRELOAD = 'l',
FLAG_DEBUG = 'g',
FLAG_ACTION = 'a',
FLAG_HELP = 'h',
Expand All @@ -462,6 +598,7 @@ int main(int argc, char *const *argv)
{"core", no_argument, NULL, FLAG_CORE},
{"debug", no_argument, NULL, FLAG_DEBUG},
{"import-path", required_argument, NULL, FLAG_IMPORT_PATH},
{"preload", required_argument, NULL, FLAG_PRELOAD},
{"action", required_argument, NULL, FLAG_ACTION},
{"history-file", required_argument, NULL, FLAG_HISTORY_FILE},
{"history-limit", required_argument, NULL, FLAG_HISTORY_LIMIT},
Expand All @@ -475,7 +612,7 @@ int main(int argc, char *const *argv)
DefaultOptions(&options);

int option, i = 1;
while ((option = getopt_long(argc, argv, "gf:OI:a:hv", flags, &i)) != -1) {
while ((option = getopt_long(argc, argv, "gf:OI:l:a:hv", flags, &i)) != -1) {
switch (option) {
case FLAG_BLIMP_OPTION: {
const char *error = Blimp_ParseOption(
Expand Down Expand Up @@ -513,6 +650,18 @@ int main(int argc, char *const *argv)
options.import_path[options.import_path_len-1] = NULL;
break;

case FLAG_PRELOAD:
options.prepend = realloc(
options.prepend,
++options.prepend_len * sizeof(char *)
);
if (options.prepend == NULL) {
perror("could not allocate preload");
return EXIT_FAILURE;
}
options.prepend[options.prepend_len-1] = optarg;
break;

case FLAG_ACTION:
if (strcmp(optarg, "eval") == 0) {
options.action = ACTION_EVAL;
Expand Down Expand Up @@ -575,22 +724,22 @@ int main(int argc, char *const *argv)

Blimp_Check(BlimpModule_Init(blimp, options.import_path));

// Automatically import the `std' prelude if requested by the user.
// Automatically prepend the `std' prelude if requested by the user.
if (options.implicit_prelude) {
BlimpObject *std;
Blimp_Check(BlimpModule_Import(
blimp,
"std",
Blimp_GlobalObject(blimp),
options.import_path,
&std
));
BlimpObject_Release(std);
options.prepend = realloc(
options.prepend, ++options.prepend_len * sizeof(char *));
if (options.prepend == NULL) {
fprintf(stderr, "could not allocate preload");
return EXIT_FAILURE;
}
options.prepend[options.prepend_len-1] = "std";
}

if (optind == argc) {
options.interactive = true;
return ReplMain(blimp, &options);
} else if (optind + 1 == argc) {
options.interactive = false;
return EvalMain(blimp, argv[optind], &options);
} else {
PrintUsage(stderr, argc, argv);
Expand Down
6 changes: 5 additions & 1 deletion blimp/src/options.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,8 @@
void DefaultOptions(Options *options)
{
options->blimp_options = DEFAULT_BLIMP_OPTIONS;
options->action = ACTION_EVAL;
options->action = ACTION_DEFAULT;
options->interactive = false;

// By default, we look for modules in the current working directory, the
// directory containing the standard extension modules (e.g. `system`), and
Expand All @@ -17,6 +18,9 @@ void DefaultOptions(Options *options)
options->import_path[1] = PRELUDE_PATH;
options->import_path[2] = EXTENSIONS_PATH;

options->prepend_len = 0;
options->prepend = NULL;

const char *home = getenv("HOME");
char *history_file = NULL;
if (home) {
Expand Down
6 changes: 5 additions & 1 deletion blimp/src/options.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@
#include <blimp.h>

typedef enum {
ACTION_DEFAULT,
ACTION_EVAL,
ACTION_PARSE,
ACTION_DUMP,
Expand All @@ -12,12 +13,15 @@ typedef enum {

typedef struct {
BlimpOptions blimp_options;

bool interactive;
Action action;

size_t import_path_len;
const char **import_path;

size_t prepend_len;
const char **prepend;

const char *history_file;
size_t history_limit;
bool no_history_limit;
Expand Down
16 changes: 16 additions & 0 deletions core/include/blimp.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -895,6 +895,22 @@ BlimpStatus Blimp_OpenFileStream(
BlimpStatus Blimp_StringStream(
Blimp *blimp, const char *str, BlimpStream **stream);

/**
* \brief Create a new stream which outputs the contents of `s1` and then `s2`.
*
* This function takes ownership of both `s1` and `s2`. After this function
* returns successfully, the caller should no longer use `s1` or `s2`.
*/
BlimpStatus Blimp_ConcatStreams(
Blimp *blimp, BlimpStream *s1, BlimpStream *s2, BlimpStream **stream);

/**
* \brief Close and deallocate a stream which was allocated using malloc().
*
* This function can be used with all of the built-in stream types.
*/
void BlimpStream_Delete(BlimpStream *stream);

void Blimp_DumpGrammarVitals(FILE *file, Blimp *blimp);

typedef size_t BlimpTerminal;
Expand Down
2 changes: 1 addition & 1 deletion core/include/internal/parse.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -10,7 +10,7 @@

PRIVATE Status Stream_Next(Stream *stream, int *c);
PRIVATE SourceLoc Stream_Location(Stream *stream);
PRIVATE void Stream_Delete(Stream *stream);
#define Stream_Delete BlimpStream_Delete

typedef enum {
TOK_MSG_NAME,
Expand Down
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