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diff --git a/src/old binding.txt b/src/old binding.txt
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+//! This file provides the Emacs binding for the core.
+
+#![allow(unused_imports)]
+
+extern crate repcore;
+
+use repcore::{
+    derive::stdag::{PFRecorder, STDAGParser},
+    grammar::{Grammar, GrammarInfo},
+    semiring::{IdentityRecorder, Nat, PFS},
+    tokenizer::to_tokenizer,
+    valuation::{Count, ParseForest},
+};
+
+use repcore::parser::Parser as PParser;
+use repcore::parser::ParserReportConfig as PParserConfig;
+
+// TODO: Write Emacs binding
+
+// Let's design the API for Emacs to use.
+//
+// Emacs offers the grammar file or grammar string, and then we
+// generate a parser.
+//
+// Thereafter when we want to parse some input, Emacs gives the input
+// file name or the input file string to this package, and then the
+// package gives back the parse result.
+//
+// Besides, we need a data type to deal with errors.
+//
+// Handling a string is not a problem for us, but to return a parser
+// to Emacs, and to return the parse result, are kind of troublesome.
+//
+// To achieve this, we need data types for a parser and for the parse
+// result.  Since a parser is just an implementation detail and should
+// not be of concern to the user, we mught just represent a parser as
+// just a custom user-ptr in Emacs.
+//
+// As to the parse result, we return a set of tuples:
+//
+// (label, i, k, j),
+//
+// where LABEL is represented as a tuple
+//
+// (INDEX, STRING),
+//
+// where index is the index of the rule and the string is the name of
+// the non-terminal or the terminal that is spanned by this packed
+// node.
+//
+// This is not intended for the user to inspect and play with.  The
+// package should provide another function to interpret this data, for
+// example to search something or to display it.  The reason we don't
+// directly return something to display is that the plain forest might
+// contain cyclic data, and is inconvenient to represent in Emacs.  So
+// we only try to display this information to the user if the need
+// arises.
+
+#[derive(Debug, Clone)]
+#[repr(C)]
+pub struct Parser {
+    g: Grammar,
+    gi: GrammarInfo,
+    stparser: STDAGParser<PFS, ParseForest, PFRecorder>,
+}
+
+impl Parser {
+    fn new(gs: &str) -> Result<Self, Box<dyn std::error::Error>> {
+        let g: Grammar = gs.parse()?;
+
+        let mut stparser = STDAGParser::new();
+
+        let mut gi = g.generate_info()?;
+
+        stparser.init(&g, &mut gi)?;
+
+        Ok(Self { g, gi, stparser })
+    }
+}
+
+#[no_mangle]
+extern "C" fn new_parser(
+    gs: *mut std::os::raw::c_char,
+    error: *mut std::os::raw::c_int,
+) -> *mut Parser {
+    let parsed_str;
+    let parser_result;
+
+    unsafe {
+        let cstr = std::ffi::CStr::from_ptr(gs).to_str();
+
+        if cstr.is_err() {
+            *error = 1;
+            return std::ptr::null_mut();
+        }
+
+        parsed_str = cstr.unwrap().to_owned();
+
+        parser_result = Parser::new(&parsed_str);
+
+        if parser_result.is_err() {
+            *error = 2;
+            eprintln!("failed: {parser_result:?}");
+            return std::ptr::null_mut();
+        }
+
+        *error = 0;
+    }
+
+    Box::into_raw(Box::new(parser_result.unwrap()))
+}
+
+#[no_mangle]
+extern "C" fn clean_parser(parser: *const std::ffi::c_void) {
+    unsafe {
+        Box::from_raw(parser as *mut Parser);
+    }
+}
+
+// #[no_mangle]
+// extern "C" fn reset_parser(parser: *mut Parser) {
+//     let mut parser_box;
+//     unsafe {
+//         parser_box = Box::from_raw(parser);
+//     }
+
+//     parser_box
+//         .stparser
+//         .init(&parser_box.g, &parser_box.gi)
+//         .unwrap();
+
+//     std::mem::forget(parser_box);
+// }
+
+// FIXME: Use a pointer to int to indicate the type of errors, and use
+// a pointer to a custom error struct to convey the error messages.
+#[no_mangle]
+extern "C" fn parser_parse(
+    parser: *mut Parser,
+    file: *const std::os::raw::c_char,
+) -> std::os::raw::c_int {
+    let mut parser_box;
+    let cstr;
+
+    unsafe {
+        parser_box = Box::from_raw(parser);
+        cstr = std::ffi::CStr::from_ptr(file).to_str();
+
+        if cstr.is_err() {
+            eprintln!("error reading string: {:?}", cstr);
+            return 0;
+        }
+    }
+
+    parser_box.stparser.reinit();
+
+    let file_string = std::fs::read_to_string(cstr.unwrap());
+
+    if file_string.is_err() {
+        eprintln!("error reading file: {:?}", file_string);
+        return 0;
+    }
+
+    let file_string = file_string.unwrap();
+
+    let parse_result = parser_box
+        .stparser
+        .parse(&file_string.chars().collect::<Vec<_>>());
+
+    if parse_result.is_err() {
+        eprintln!("failed to parse: {:?}", parse_result);
+        return 0;
+    }
+
+    let (accepting, _) = parse_result.unwrap();
+
+    std::mem::forget(parser_box);
+
+    accepting as std::os::raw::c_int
+}
+
+#[no_mangle]
+extern "C" fn parser_parse_string(
+    parser: *mut Parser,
+    input: *const std::os::raw::c_char,
+) -> std::os::raw::c_int {
+    let mut parser_box;
+    let cstr;
+
+    unsafe {
+        parser_box = Box::from_raw(parser);
+        cstr = std::ffi::CStr::from_ptr(input).to_str();
+
+        if cstr.is_err() {
+            eprintln!("error reading string: {:?}", cstr);
+            return 0;
+        }
+    }
+
+    parser_box.stparser.reinit();
+
+    let file_string = cstr.unwrap().to_owned();
+
+    let parse_result = parser_box
+        .stparser
+        .parse(&file_string.chars().collect::<Vec<_>>());
+
+    if parse_result.is_err() {
+        eprintln!("failed to parse: {:?}", parse_result);
+        return 0;
+    }
+
+    let (accepting, _) = parse_result.unwrap();
+
+    std::mem::forget(parser_box);
+
+    accepting as std::os::raw::c_int
+}