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Userland: Implement JS REPL

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If you invoke `js` without a script path, it will now enter REPL mode,
where you input commands one by one and immediately get each one
interpreted in one shared interpreter. We support multi-line commands
in case we detect you have unclosed braces or parens or brackets.
This commit is contained in:
Sergey Bugaev 2020-03-26 01:10:29 +03:00 committed by Andreas Kling
parent 5bb18bf548
commit ccdfb077d8
Notes: sideshowbarker 2024-07-19 08:07:25 +09:00 
Author: https://github.com/bugaevc
Commit: https://github.com/SerenityOS/serenity/commit/ccdfb077d8f
1 changed files with 100 additions and 28 deletions
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128
Userland/js.cpp
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@ -26,6 +26,7 @@
#include <AK/ByteBuffer.h>
#include <AK/NonnullOwnPtr.h>
#include <AK/StringBuilder.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/File.h>
#include <LibJS/AST.h>
@ -36,11 +37,79 @@
#include <LibJS/Runtime/Value.h>
#include <stdio.h>
#define PROGRAM 6
bool dump_ast = false;
String read_next_piece()
{
StringBuilder piece;
int level = 0;
do {
if (level == 0)
fprintf(stderr, "> ");
else
fprintf(stderr, ".%*c", 4 * level + 1, ' ');
char* line = nullptr;
size_t allocated_size = 0;
ssize_t nread = getline(&line, &allocated_size, stdin);
if (nread < 0) {
if (errno == ESUCCESS) {
// Explicit EOF; stop reading. Print a newline though, to make
// the next prompt (or the shell prompt) appear on the next
// line.
fprintf(stderr, "\n");
break;
} else {
perror("getline");
exit(1);
}
}
piece.append(line);
auto lexer = JS::Lexer(line);
for (JS::Token token = lexer.next(); token.type() != JS::TokenType::Eof; token = lexer.next()) {
switch (token.type()) {
case JS::TokenType::BracketOpen:
case JS::TokenType::CurlyOpen:
case JS::TokenType::ParenOpen:
level++;
break;
case JS::TokenType::BracketClose:
case JS::TokenType::CurlyClose:
case JS::TokenType::ParenClose:
level--;
break;
default:
break;
}
}
free(line);
} while (level > 0);
return piece.to_string();
}
void repl(JS::Interpreter& interpreter)
{
while (true) {
String piece = read_next_piece();
if (piece.is_empty())
break;
auto program = JS::Parser(JS::Lexer(piece)).parse_program();
if (dump_ast)
program->dump(0);
auto result = interpreter.run(*program);
printf("%s\n", result.to_string().characters());
}
}
int main(int argc, char** argv)
{
bool dump_ast = false;
bool gc_on_every_allocation = false;
bool print_last_result = false;
const char* script_path = nullptr;
@ -49,40 +118,43 @@ int main(int argc, char** argv)
args_parser.add_option(dump_ast, "Dump the AST", "ast-dump", 'A');
args_parser.add_option(print_last_result, "Print last result", "print-last-result", 'l');
args_parser.add_option(gc_on_every_allocation, "GC on every allocation", "gc-on-every-allocation", 'g');
args_parser.add_positional_argument(script_path, "Path to script file", "script");
args_parser.add_positional_argument(script_path, "Path to script file", "script", Core::ArgsParser::Required::No);
args_parser.parse(argc, argv);
auto file = Core::File::construct(script_path);
if (!file->open(Core::IODevice::ReadOnly)) {
fprintf(stderr, "Failed to open %s: %s\n", script_path, file->error_string());
return 1;
}
auto file_contents = file->read_all();
StringView source;
if (file_contents.size() >= 2 && file_contents[0] == '#' && file_contents[1] == '!') {
size_t i = 0;
for (i = 2; i < file_contents.size(); ++i) {
if (file_contents[i] == '\n')
break;
}
source = StringView((const char*)file_contents.data() + i, file_contents.size() - i);
} else {
source = file_contents;
}
JS::Interpreter interpreter;
interpreter.heap().set_should_collect_on_every_allocation(gc_on_every_allocation);
auto program = JS::Parser(JS::Lexer(source)).parse_program();
if (script_path == nullptr) {
repl(interpreter);
} else {
auto file = Core::File::construct(script_path);
if (!file->open(Core::IODevice::ReadOnly)) {
fprintf(stderr, "Failed to open %s: %s\n", script_path, file->error_string());
return 1;
}
auto file_contents = file->read_all();
if (dump_ast)
program->dump(0);
StringView source;
if (file_contents.size() >= 2 && file_contents[0] == '#' && file_contents[1] == '!') {
size_t i = 0;
for (i = 2; i < file_contents.size(); ++i) {
if (file_contents[i] == '\n')
break;
}
source = StringView((const char*)file_contents.data() + i, file_contents.size() - i);
} else {
source = file_contents;
}
auto program = JS::Parser(JS::Lexer(source)).parse_program();
auto result = interpreter.run(*program);
if (dump_ast)
program->dump(0);
if (print_last_result)
printf("%s\n", result.to_string().characters());
auto result = interpreter.run(*program);
if (print_last_result)
printf("%s\n", result.to_string().characters());
}
return 0;
}