xo-reader2: working on example parser repl

This commit is contained in:
Roland Conybeare 2026-01-22 21:03:40 -05:00
commit 8c038ed669
8 changed files with 393 additions and 2 deletions

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@ -0,0 +1,146 @@
/** @file readerreplxx.cpp **/
#include "xo/reader/reader.hpp"
#include <replxx.hxx>
#include <iostream>
#include <unistd.h> // for isatty
// presumeably replxx assumes input is a tty
//
bool replxx_getline(bool interactive,
std::size_t parser_stack_size,
replxx::Replxx & rx,
const char ** p_input)
{
using namespace std;
char const * prompt = "";
if (interactive) {
if (parser_stack_size <= 1)
prompt = "> ";
else
prompt = ". ";
}
const char * input_cstr = rx.input(prompt);
bool retval = (input_cstr != nullptr);
if (retval) {
//cerr << "got reval->true" << endl;
input = input_cstr;
} else {
//cerr << "got retval->false" << endl;
}
rx.history_add(input);
return retval;
}
void
welcome(std::ostream& os)
{
using namespace std;
os << "read-eval-print loop for schematika expressions" << endl;
os << " ctrl-a/ctrl-e beginning/end of line" << endl;
os << " ctrl-u delete entire line" << endl;
os << " ctrl-k delete to end of line" << endl;
os << " meta-<bs> backward delete word" << endl;
os << " <up>|meta-p previous command from history" << endl;
os << " <down>|meta-n next command from history" << endl;
os << " <pgup>/<pgdown> page through history faster" << endl;
os << " ctrl-s/ctrl-r forward/backward history search" << endl;
os << endl;
}
int
main()
{
using namespace replxx;
using namespace xo::scm;
using xo::scm::Expression;
using xo::print::ppconfig;
using xo::print::ppstate_standalone;
using xo::rp;
using namespace std;
using span_type = xo::scm::span<const char>;
bool interactive = isatty(STDIN_FILENO);
Replxx rx;
rx.set_max_history_size(1000);
rx.history_load("repl_history.txt");
// rx.bind_key_internal(Replxx::KEY::control('p'), "history_previous");
// rx.bind_key_internal(Replxx::KEY::control('n'), "history_next");
constexpr bool c_debug_flag = false;
scope log(XO_DEBUG(c_debug_flag));
DArena expr_arena = DArena::map(ArenaConfig{ .name_ = "expr-arena", .size_ = 2*1024*1024; });
obj<AAllocator> expr_alloc = with_facet<AAllocator>::mkobj(&expr_arena);
constexpr size_t c_max_stringtable_cap = 1024*1024;
SchematikaParser parser(expr_arena.config_, c_max_stringtable_cap, expr_alloc, c_debug_flag);
parser.begin_interactive_session();
string input_str;
bool eof = false;
span_type input;
std::size_t parser_stack_size = 0;
welcome(cerr);
while (replxx_getline(interactive, parser_stack_size, rx, input_str)) {
input = span_type::from_string(input_str);
while (!input.empty()) {
auto [expr, consumed, psz, error] = rdr.read_expr(input, eof);
if (expr) {
ppconfig ppc;
ppstate_standalone pps(&cout, 0, &ppc);
pps.prettyn(expr);
} else if (error.is_error()) {
cout << "parsing error (detected in " << error.src_function() << "): " << endl;
error.report(cout);
/* discard stashed remainder of input line
* (for nicely-formatted errors)
*/
rdr.reset_to_idle_toplevel();
break;
}
input = input.after_prefix(consumed);
parser_stack_size = psz;
}
/* here: input.empty() or error encountered */
}
auto [expr, _1, _2, error] = rdr.read_expr(input, true /*eof*/);
if (expr) {
ppconfig ppc;
ppstate_standalone pps(&cout, 0, &ppc);
pps.prettyn<rp<Expression>>(rp<Expression>(expr));
} else if (error.is_error()) {
cout << "parsing error (detected in " << error.src_function() << "): " << endl;
error.report(cout);
}
rx.history_save("repl_history.txt");
}
/* end readerreplxx.cpp */

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@ -67,7 +67,7 @@ namespace xo {
/** pretty-printing support **/
bool pretty(const ppindentinfo & ppii) const;
private:
public:
/** none|expression|error_description
*
* @text

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@ -0,0 +1,54 @@
/** @file ReaderConfig.hpp
*
* @author Roland Conybeare, Jan 2026
**/
#pragma once
#include <xo/arena/CircularBufferConfig.hpp>
#include <xo/arena/ArenaConfig.hpp>
namespace xo {
namespace scm {
/** @brief Configuration for SchemtikaReader
**/
struct ReaderConfig {
using CircularBufferConfig = xo::mm::CircularBufferConfig;
using ArenaConfig = xo::mm::ArenaConfig;
using size_t = std::size_t;
/** tokenizer circular buffer config **/
CircularBufferConfig tk_buffer_config_ {.name_ = "tk-buffer",
.max_capacity_ = 2*1024*1024,
.hugepage_z_ = 2*1024*1024,
.threshold_move_efficiency_ = 50.0,
.max_captured_span_ = 128 };
/** debug flag for schematika tokenizer **/
bool tk_debug_flag_ = false;
/** arena configuration for parser stack **/
ArenaConfig parser_arena_config_ { .name_ = "parer-arena",
.size_ = 2*1024*1024,
.hugepage_z_ = 2*1024*1024,
.store_header_flag_ = false,
.header_{},
.debug_flag_ = false };
/** max size (in bytes) of stringtable **/
size_t max_stringtable_cap_ = 64*1024;
/** debug flag for schematika parser **/
bool parser_debug_flag_ = false;
#ifdef NOT_YET
/** arena configuration for output expressions **/
ArenaConfig expr_arena_config_ { .name_ = "expr-arena",
.size_ = 2*1024*1024,
.hugepage_z_ = 2*1024*1024,
.store_header_flag_ = false,
.header_{},
.debug_flag_ = false };
#endif
};
} /*namespace scm*/
} /*namepspace xo*/
/* end ReaderConfig.hpp */

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@ -162,7 +162,7 @@ namespace xo {
/** create parser in initial state;
* parser is ready to receive tokens via @ref include_token
*
* @p config arena configuration for parser memory
* @p config arena configuration for parser stack
* @p expr_alloc allocator for schematika expressions.
* Probably shared with execution.
* @p debug_flag true to enable debug logging

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@ -0,0 +1,70 @@
/** @file SchematikaReader.hpp
*
* @author Roland Conybeare, Jan 2026
**/
#pragma once
#include "ReaderConfig.hpp"
#include "SchematikaParser.hpp"
#include <xo/tokenizer2/Tokenizer.hpp>
namespace xo {
namespace scm {
struct ReaderResult {
using span_type = xo::mm::span<const char>;
bool is_tk_error() const { return tk_error_.is_error(); }
/** schematika expression parsed from input **/
obj<AExpression> expr_;
/** input span up to end of expression.
* only relevant when result type is expression.
* (otherwise treat entire input as consumed)
**/
span_type consumed_;
/** {src_function, error_description, input_state, error_pos} **/
TokenizerError tk_error_;
};
/** @class SchematikaReader
* @brief Pipeline comprising Schematika tokenizer and parser
*
* Consumes text; produces expressions
**/
class SchematikaReader {
public:
using AAllocator = xo::mm::AAllocator;
public:
SchematikaReader(const ReaderConfig & config,
obj<AAllocator> expr_alloc);
/** prepare interactive session
* (allows rvalue expressions at toplevel)
**/
void begin_interactive_session();
/** consume input @p input_cstr **/
const ReaderResult & read_expr(const char * input_cstr, bool eof);
private:
/** tokenizer converts a stream of chars
* to a stream of lexical tokens
**/
Tokenizer tokenizer_;
/** parser converts a stream of tokens
* to a stream of expressions
**/
SchematikaParser parser_;
/** current output from reader **/
ReaderResult result_;
};
} /*namespace scm*/
} /*namespace xo*/
/* end SchematikaReader.hpp */

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@ -4,6 +4,9 @@ set(SELF_LIB xo_reader2)
set(SELF_SRCS
init_reader2.cpp
SchematikaReader.cpp
ReaderConfig.cpp
SchematikaParser.cpp
ParserStateMachine.cpp
ParserStack.cpp

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@ -0,0 +1,13 @@
/** @file ReaderConfig.cpp
*
* @author Roland Conybeare, Jan 2026
**/
#include "ReaderConfig.hpp"
namespace xo {
namespace scm {
}
} /*namespace xo*/
/* end ReaderConfig.cpp */

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@ -0,0 +1,105 @@
/** @file SchematikaReader.cpp
*
* @author Roland Conybeare, Jan 2026
**/
#include "SchematikaReader.hpp"
namespace xo {
namespace scm {
SchematikaReader::SchematikaReader(const ReaderConfig & config,
obj<AAllocator> expr_alloc)
: tokenizer_{config.tk_buffer_config_, config.tk_debug_flag_},
parser_{config.parser_arena_config_,
config.max_stringtable_cap_,
expr_alloc,
config.parser_debug_flag_}
{
}
void
SchematikaReader::begin_interactive_session()
{
parser_.begin_interactive_session();
}
// TODO:
// Schematika::end_interactive_session()
const ReaderResult &
SchematikaReader::read_expr(const char * input_cstr, bool eof)
{
if (input_cstr && *input_cstr) {
auto [error, input]
= tokenizer_.buffer_input_line(input_cstr,
false /*!eof*/);
// log && log(xtag("msg", "buffered input line"));
// log && log(xtag("input", input));
while (!input.empty()) {
auto [tk, consumed, error] = tkz.scan(input);
if (!tk.is_valid() && error.is_error()) {
this->result_ = ReaderResult { .expr_ = obj<AExpression>(),
.tk_error_ = std::move(error),
.consumed_ = nullptr };
return result_;
}
// log && log(xtag("consumed", consumed), xtag("tk", tk));
if (tk.is_valid()) {
// presult {
// result_type :: parser_result_type = none|expression|error
// result_expr :: obj<AExpression>
// error_src_function :: string_view
// error_description :: const DString *
// }
//
const ParserResult & presult = parser_include_token(tk);
if (presult.is_error()) {
// tk_error {
// src_function :: const char *
// error_description :: string
// input_state {
// current_line :: span
// tk_start :: size_t
// current_pos :: size_t
// whitespace :: size_t
// debug_flag :: bool
// }
// error_pos :: size_t
// }
//
// tk_error.report(cout);
this->result_ = ReaderResult { .expr = obj<AExpression>(),
.tk_error_ = std::move(error),
.consumed_ = nullptr };
// carefully created error description, maybe
this->result.tk_error_.error_description_ = presult.error_description_;
}
xxxx;
} else if (error.is_error()) {
xxxx;
// error.report(cout);
break;
}
input = input.after_prefix(consumed);
}
}
++line_no;
}
} /*namespace scm*/
} /*namespace xo*/
/* end SchematikaReader.cpp */