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//! Build script for rusty_lr
//!
//! This crate is private and not intended to be used directly.
//! Please use the [`rusty_lr`](https://crates.io/crates/rusty_lr) crate instead.
//!
//! ```no_run
//! fn main() {
//!     println!("cargo::rerun-if-changed=src/parser/parser.rs");
//!
//!     let output_dir = std::env::var("OUT_DIR").unwrap();
//!     let output = format!("{}/parser.rs", output_dir);
//!     Builder::new()
//!        .file("src/parser/parser.rs")
//!        .build(&output);
//! }
//!

pub mod output;
mod split;
mod utils;

use codespan_reporting::diagnostic::Diagnostic;
use codespan_reporting::diagnostic::Label;
use codespan_reporting::files::SimpleFiles;
use codespan_reporting::term;
use codespan_reporting::term::termcolor::ColorChoice;
use codespan_reporting::term::termcolor::StandardStream;

use proc_macro2::Ident;
use proc_macro2::Span;
use proc_macro2::TokenStream;

use quote::quote;
use rusty_lr_core::ShiftedRule;
use rusty_lr_parser::error::ArgError;
use rusty_lr_parser::error::EmitError;
use rusty_lr_parser::error::ParseArgError;
use rusty_lr_parser::error::ParseError;

use std::collections::BTreeMap;
use std::collections::BTreeSet;
use std::fs::read;
use std::fs::write;

/// Main entry for the build script
pub struct Builder {
    /// input_file to read
    input_file: Option<String>,

    /// when `vebose` is on, print debug information about
    /// any shift/reduce, reduce/reduce conflicts.
    /// This is for GLR parser, to show where the conflicts occured.
    verbose_conflicts: bool,

    /// when `vebose` is on, print debug information about
    /// conflicts resolving process by `%left` or `%right` for any shift/reduce, reduce/reduce conflicts.
    verbose_conflicts_resolving: bool,

    /// print verbose information to stderr
    verbose_on_stderr: bool,
}

impl Builder {
    pub fn new() -> Self {
        Self {
            input_file: None,
            verbose_conflicts: false,
            verbose_conflicts_resolving: false,
            verbose_on_stderr: false,
        }
    }

    /// set input file
    pub fn file(&mut self, filename: &str) -> &mut Self {
        self.input_file = Some(filename.to_string());
        self
    }

    /// turns on all verbose options
    pub fn verbose(&mut self) -> &mut Self {
        self.verbose_conflicts();
        self.verbose_conflicts_resolving();
        self
    }

    /// when `vebose` is on, print debug information about
    /// any shift/reduce, reduce/reduce conflicts.
    pub fn verbose_conflicts(&mut self) -> &mut Self {
        self.verbose_conflicts = true;
        self
    }

    /// when `vebose` is on, print debug information about
    /// conflicts resolving process by `%left` or `%right` for any shift/reduce, reduce/reduce conflicts.
    pub fn verbose_conflicts_resolving(&mut self) -> &mut Self {
        self.verbose_conflicts_resolving = true;
        self
    }

    /// print debug information to stderr.
    pub fn verbose_on_stderr(&mut self) -> &mut Self {
        self.verbose_on_stderr = true;
        self
    }

    fn verbose_stream(&self) -> StandardStream {
        if self.verbose_on_stderr {
            StandardStream::stderr(ColorChoice::Auto)
        } else {
            StandardStream::stdout(ColorChoice::Auto)
        }
    }

    /// build and emit code to output file
    pub fn build(&self, output_file: &str) {
        let output = match self.build_impl() {
            Ok(output) => {
                let stream1 = output.user_stream;
                let stream2 = output.generated_stream;
                quote! {
                    #stream1
                    #stream2
                }
            }
            Err(_) => {
                panic!("build failed");
            }
        };

        write(output_file, output.to_string()).expect("Failed to write to file");
    }

    /// extend `labels` with messages about the source of the rule
    /// if `ruleid` is auto-generated rule, "{} was generated here" will be added
    /// if `ruleid` is user-written rule, "{} was defined here" will be added
    fn extend_rule_source_label(
        labels: &mut Vec<codespan_reporting::diagnostic::Label<usize>>,
        fileid: usize,
        ruleid: usize,
        grammar: &rusty_lr_parser::grammar::Grammar,
        prefix_str: &str,
    ) {
        let (nonterm, local_rule) = grammar.get_rule_by_id(ruleid).expect("Rule not found");
        if let Some(origin_span) = &nonterm.regex_span {
            let origin_range = origin_span.0.byte_range().start..origin_span.1.byte_range().end;
            labels.push(Label::primary(fileid, origin_range).with_message(format!(
                "{}{} was generated here",
                prefix_str, nonterm.pretty_name,
            )));
        } else {
            let (rule_begin, rule_end) = nonterm.rules[local_rule].span_pair();
            let rule_range = rule_begin.byte_range().start..rule_end.byte_range().end;

            labels.push(
                Label::primary(fileid, nonterm.name.span().byte_range()).with_message(format!(
                    "{}{} was defined here",
                    prefix_str, nonterm.pretty_name
                )),
            );
            labels.push(
                Label::secondary(fileid, rule_range).with_message("in this line".to_string()),
            );
        }
    }

    /// for internal use
    pub fn build_impl(&self) -> Result<output::Output, String> {
        if self.input_file.is_none() {
            eprintln!("Input file not set");
            return Err("Input file not set".to_string());
        }

        let input_file = self.input_file.as_ref().unwrap();
        // read file
        let input_bytes = match read(input_file) {
            Ok(bytes) => bytes,
            Err(e) => {
                let message = format!("Error reading file: {}", e);
                eprintln!("{}", message);
                return Err(message);
            }
        };

        let str = match String::from_utf8(input_bytes) {
            Ok(str) => str,
            Err(e) => {
                let message = format!("Error reading utf-8: {}", e);
                eprintln!("{}", message);
                return Err(message);
            }
        };

        let mut files = SimpleFiles::new();
        let file_id = files.add(input_file, str.clone());

        // lex with proc-macro2
        let token_stream: TokenStream = match str.parse() {
            Ok(token_stream) => token_stream,
            Err(e) => {
                let range = e.span().byte_range();
                let diag = Diagnostic::error()
                    .with_message("Lexing error")
                    .with_labels(vec![
                        Label::primary(file_id, range).with_message(e.to_string())
                    ]);
                let writer = StandardStream::stderr(ColorChoice::Auto);
                let config = codespan_reporting::term::Config::default();
                term::emit(&mut writer.lock(), &config, &files, &diag)
                    .expect("Failed to write to stderr");
                return Err("Lexing error".to_string());
            }
        };

        // split stream by '%%'
        let (output_stream, macro_stream) = match split::split_stream(token_stream) {
            Ok((output_stream, macro_stream)) => (output_stream, macro_stream),
            Err(_) => {
                let diag = Diagnostic::error()
                    .with_message("Cannot find `%%`")
                    .with_notes(vec![
                    "Please put `%%` to separate the code part and the context-free grammar part"
                        .to_string(),
                ]);
                let writer = StandardStream::stderr(ColorChoice::Auto);
                let config = codespan_reporting::term::Config::default();
                term::emit(&mut writer.lock(), &config, &files, &diag)
                    .expect("Failed to write to stderr");
                return Err(diag.message);
            }
        };

        let grammar_args = match rusty_lr_parser::grammar::Grammar::parse_args(macro_stream) {
            Ok(grammar_args) => grammar_args,
            Err(e) => {
                let diag =
                    match e {
                        ParseArgError::MacroLineParse { span, message } => {
                            let range = span.byte_range();

                            Diagnostic::error()
                                .with_message("Parse Failed")
                                .with_labels(vec![
                                    Label::primary(file_id, range).with_message("Error here")
                                ])
                                .with_notes(vec![message])
                        }
                        ParseArgError::MacroLineParseEnd { message } => Diagnostic::error()
                            .with_message("Parse Failed")
                            .with_notes(vec![message]),

                        _ => {
                            let message = e.short_message();
                            let span = e.span().byte_range();
                            Diagnostic::error().with_message(message).with_labels(vec![
                                Label::primary(file_id, span).with_message("occured here"),
                            ])
                        }
                    };

                let writer = StandardStream::stderr(ColorChoice::Auto);
                let config = codespan_reporting::term::Config::default();
                term::emit(&mut writer.lock(), &config, &files, &diag)
                    .expect("Failed to write to stderr");
                return Err(diag.message);
            }
        };
        match rusty_lr_parser::grammar::Grammar::arg_check_error(&grammar_args) {
            Ok(_) => {}
            Err(e) => {
                let diag = match e {
                    ArgError::MultipleModulePrefixDefinition(
                        (span1, tokenstream1),
                        (span2, tokenstream2),
                    ) => {
                        let range1 = utils::span_stream_range(span1, tokenstream1);
                        let range2 = utils::span_stream_range(span2, tokenstream2);

                        Diagnostic::error()
                            .with_message("Multiple %moduleprefix definition")
                            .with_labels(vec![
                                Label::primary(file_id, range1).with_message("First definition"),
                                Label::primary(file_id, range2).with_message("Other definition"),
                            ])
                            .with_notes(vec![
                                "Only one %moduleprefix definition is allowed".to_string()
                            ])
                    }
                    ArgError::MultipleUserDataDefinition(
                        (span1, tokenstream1),
                        (span2, tokenstream2),
                    ) => {
                        let range1 = utils::span_stream_range(span1, tokenstream1);
                        let range2 = utils::span_stream_range(span2, tokenstream2);

                        Diagnostic::error()
                            .with_message("Multiple %userdata definition")
                            .with_labels(vec![
                                Label::primary(file_id, range1).with_message("First definition"),
                                Label::primary(file_id, range2).with_message("Other definition"),
                            ])
                            .with_notes(
                                vec!["Only one %userdata definition is allowed".to_string()],
                            )
                    }
                    ArgError::MultipleErrorDefinition(
                        (span1, tokenstream1),
                        (span2, tokenstream2),
                    ) => {
                        let range1 = utils::span_stream_range(span1, tokenstream1);
                        let range2 = utils::span_stream_range(span2, tokenstream2);

                        Diagnostic::error()
                            .with_message("Multiple %error definition")
                            .with_labels(vec![
                                Label::primary(file_id, range1).with_message("First definition"),
                                Label::primary(file_id, range2).with_message("Other definition"),
                            ])
                            .with_notes(vec!["Only one %error definition is allowed".to_string()])
                    }
                    ArgError::MultipleTokenTypeDefinition(
                        (span1, tokenstream1),
                        (span2, tokenstream2),
                    ) => {
                        let range1 = utils::span_stream_range(span1, tokenstream1);
                        let range2 = utils::span_stream_range(span2, tokenstream2);

                        Diagnostic::error()
                            .with_message("Multiple %tokentype definition")
                            .with_labels(vec![
                                Label::primary(file_id, range1).with_message("First definition"),
                                Label::primary(file_id, range2).with_message("Other definition"),
                            ])
                            .with_notes(vec![
                                "Only one %tokentype definition is allowed".to_string()
                            ])
                    }
                    ArgError::MultipleEofDefinition(
                        (span1, tokenstream1),
                        (span2, tokenstream2),
                    ) => {
                        let range1 = utils::span_stream_range(span1, tokenstream1);
                        let range2 = utils::span_stream_range(span2, tokenstream2);

                        Diagnostic::error()
                            .with_message("Multiple %eof definition")
                            .with_labels(vec![
                                Label::primary(file_id, range1).with_message("First definition"),
                                Label::primary(file_id, range2).with_message("Other definition"),
                            ])
                            .with_notes(vec!["Only one %eof definition is allowed".to_string()])
                    }
                    ArgError::MultipleStartDefinition(ident1, ident2) => {
                        let range1 = ident1.span().byte_range();
                        let range2 = ident2.span().byte_range();

                        Diagnostic::error()
                            .with_message("Multiple %start definition")
                            .with_labels(vec![
                                Label::primary(file_id, range1).with_message("First definition"),
                                Label::primary(file_id, range2).with_message("Other definition"),
                            ])
                            .with_notes(vec!["Only one %start definition is allowed".to_string()])
                    }

                    ArgError::StartNotDefined => Diagnostic::error()
                        .with_message("%start not defined")
                        .with_labels(vec![])
                        .with_notes(vec![
                            "%start must be defined".to_string(),
                            ">>> %start <non-terminal>".to_string(),
                        ]),
                    ArgError::EofNotDefined => Diagnostic::error()
                        .with_message("%eof not defined")
                        .with_labels(vec![])
                        .with_notes(vec![
                            "%eof must be defined".to_string(),
                            ">>> %eof <terminal>".to_string(),
                        ]),
                    ArgError::TokenTypeNotDefined => Diagnostic::error()
                        .with_message("%tokentype not defined")
                        .with_labels(vec![])
                        .with_notes(vec![
                            "%tokentype must be defined".to_string(),
                            ">>> %tokentype <TokenType>".to_string(),
                        ]),
                    _ => {
                        let message = e.short_message();
                        let span = e.span().byte_range();
                        Diagnostic::error()
                            .with_message(message)
                            .with_labels(vec![
                                Label::primary(file_id, span).with_message("occured here")
                            ])
                    }
                };

                let writer = StandardStream::stderr(ColorChoice::Auto);
                let config = codespan_reporting::term::Config::default();
                term::emit(&mut writer.lock(), &config, &files, &diag)
                    .expect("Failed to write to stderr");
                return Err(diag.message);
            }
        }

        // parse lines
        let grammar = match rusty_lr_parser::grammar::Grammar::from_grammar_args(grammar_args) {
            Ok(grammar) => grammar,
            Err(e) => {
                let diag = match e {
                    ParseError::MultipleRuleDefinition(ident1, ident2) => {
                        let range1 = ident1.span().byte_range();
                        let range2 = ident2.span().byte_range();

                        Diagnostic::error()
                            .with_message("Multiple rule definition")
                            .with_labels(vec![
                                Label::primary(file_id, range1).with_message("First definition"),
                                Label::primary(file_id, range2).with_message("Other definition"),
                            ])
                            .with_notes(vec!["Rule name must be unique".to_string()])
                    }

                    ParseError::MultipleReduceDefinition { terminal, old, new } => {
                        let old_range = old.0.byte_range().start..old.1.byte_range().end;
                        let old_string = match old.2 {
                            rusty_lr_core::ReduceType::Left => "%left",
                            rusty_lr_core::ReduceType::Right => "%right",
                        };
                        let new_range = new.0.byte_range().start..new.1.byte_range().end;
                        let new_string = match new.2 {
                            rusty_lr_core::ReduceType::Left => "%left",
                            rusty_lr_core::ReduceType::Right => "%right",
                        };

                        Diagnostic::error()
                            .with_message("Multiple reduce definition")
                            .with_labels(vec![
                                Label::primary(file_id, terminal.span().byte_range()).with_message(
                                    "This terminal symbol is defined as both of %left and %right",
                                ),
                                Label::secondary(file_id, old_range)
                                    .with_message(format!("was set as {} here", old_string)),
                                Label::secondary(file_id, new_range)
                                    .with_message(format!("was set as {} here", new_string)),
                            ])
                            .with_notes(vec![
                                "Reduce type must be unique, either %left or %right".to_string()
                            ])
                    }

                    ParseError::TermNonTermConflict {
                        name,
                        terminal,
                        non_terminal,
                    } => {
                        let range = name.span().byte_range();

                        Diagnostic::error()
                            .with_message("Ambiguous token name")
                            .with_labels(vec![
                                Label::primary(file_id, range).with_message(
                                    "This name is used for both terminal and non-terminal",
                                ),
                                Label::secondary(file_id, terminal.span().byte_range())
                                    .with_message("Terminal definition here"),
                                Label::secondary(file_id, non_terminal.span().byte_range())
                                    .with_message("Non-terminal definition here"),
                            ])
                            .with_notes(vec![
                                "Terminal and non-terminal name must be unique".to_string()
                            ])
                    }

                    ParseError::InvalidTerminalRange(
                        (first, first_index, first_stream),
                        (last, last_index, last_stream),
                    ) => {
                        let range1 = first.span().byte_range();
                        let range2 = last.span().byte_range();
                        let range = range1.start..range2.end;
                        let range1 = utils::tokenstream_range(first_stream);
                        let range2 = utils::tokenstream_range(last_stream);

                        Diagnostic::error()
                        .with_message("Invalid terminal range")
                        .with_labels(vec![
                            Label::primary(file_id, range).with_message("Invalid range here"),
                            Label::secondary(file_id, range1).with_message(format!("First terminal symbol (index {})", first_index)),
                            Label::secondary(file_id, range2).with_message(format!("Last terminal symbol (index {})", last_index)),
                        ]).with_notes(vec![
                            "First terminal symbol has to be less than or equal to the last terminal symbol".to_string()
                        ])
                    }

                    ParseError::StartNonTerminalNotDefined(ident) => {
                        let range = ident.span().byte_range();

                        Diagnostic::error()
                            .with_message("Start non-terminal not defined")
                            .with_labels(vec![Label::primary(file_id, range)
                                .with_message("This name is given to %start")])
                            .with_notes(vec!["Non-terminal name must be defined".to_string()])
                    }

                    ParseError::TerminalNotDefined(ident) => {
                        let range = ident.span().byte_range();

                        Diagnostic::error()
                            .with_message("Terminal symbol not defined")
                            .with_labels(vec![Label::primary(file_id, range)
                                .with_message("This terminal symbol is not defined")])
                            .with_notes(vec!["Terminal symbol must be defined".to_string()])
                    }

                    ParseError::MultipleTokenDefinition(ident1, ident2) => {
                        let range1 = ident1.span().byte_range();
                        let range2 = ident2.span().byte_range();

                        Diagnostic::error()
                            .with_message("Multiple %token definition")
                            .with_labels(vec![
                                Label::primary(file_id, range1).with_message("First definition"),
                                Label::primary(file_id, range2).with_message("Other definition"),
                            ])
                            .with_notes(vec!["Token name must be unique".to_string()])
                    }

                    ParseError::EofDefined(ident) => {
                        let range = ident.span().byte_range();

                        Diagnostic::error()
                            .with_message("'eof' is reserved name")
                            .with_labels(vec![Label::primary(file_id, range)
                                .with_message("This name is reserved")])
                    }
                    ParseError::AugmentedDefined(ident) => {
                        let range = ident.span().byte_range();

                        Diagnostic::error()
                            .with_message("'Augmented' is reserved name")
                            .with_labels(vec![Label::primary(file_id, range)
                                .with_message("This name is reserved")])
                    }
                    _ => {
                        let message = e.short_message();
                        let span = e.span().byte_range();
                        Diagnostic::error()
                            .with_message(message)
                            .with_labels(vec![
                                Label::primary(file_id, span).with_message("occured here")
                            ])
                    }
                };

                let writer = StandardStream::stderr(ColorChoice::Auto);
                let config = codespan_reporting::term::Config::default();
                term::emit(&mut writer.lock(), &config, &files, &diag)
                    .expect("Failed to write to stderr");

                return Err(diag.message);
            }
        };

        // expand macro
        let expanded_stream = match grammar.emit_compiletime() {
            Ok(expanded_stream) => expanded_stream,
            Err(e) => {
                let diag = match e.as_ref() {
                    EmitError::RuleTypeDefinedButActionNotDefined {
                        name,
                        rule_local_id,
                    } => {
                        // `name` must not be generated rule,
                        // since it is programmically generated, it must have a proper reduce action

                        let rule_id = *grammar.nonterminals_index.get(name).unwrap();
                        let rule_line = &grammar.nonterminals[rule_id].rules[*rule_local_id];
                        let rule_line_range = if rule_line.tokens.is_empty() {
                            rule_line.separator_span.byte_range()
                        } else {
                            let first = rule_line.separator_span.byte_range().start;
                            let last = rule_line.tokens.last().unwrap().end_span.byte_range().end;
                            first..last
                        };
                        Diagnostic::error()
                            .with_message("Reduce action not defined")
                            .with_labels(vec![
                                Label::secondary(file_id, name.span().byte_range())
                                    .with_message("This rule has a type definition"),
                                Label::primary(file_id, rule_line_range)
                                    .with_message("This rule line has no reduce action"),
                            ])
                            .with_notes(vec!["".to_string()])
                    }

                    EmitError::ShiftReduceConflict {
                        term,
                        reduce_rule: (reduceid, reduce_production_rule),
                        shift_rules,
                    } => {
                        let mut message = format!(
                            "Shift/Reduce conflict:\nReduce rule:\n\t>>> {}\nShift rules:",
                            reduce_production_rule
                        );
                        for (_, shifted_rule) in shift_rules.iter() {
                            message.push_str(format!("\n\t>>> {}", shifted_rule).as_str());
                        }
                        let mut labels = Vec::new();

                        Self::extend_rule_source_label(
                            &mut labels,
                            file_id,
                            *reduceid,
                            &grammar,
                            "(Reduce) ",
                        );

                        for (shiftid, _) in shift_rules.iter() {
                            Self::extend_rule_source_label(
                                &mut labels,
                                file_id,
                                *shiftid,
                                &grammar,
                                "(Shift) ",
                            );
                        }
                        Diagnostic::error()
                            .with_message(message)
                            .with_labels(labels)
                            .with_notes(vec![
                                format!("conflict terminal: {}", term),
                                format!(
                                "Try to rearrange the rules or resolve conflict by set reduce type"
                            ),
                                format!(">>> %left {}", term),
                                format!(">>> %right {}", term),
                            ])
                    }
                    EmitError::ReduceReduceConflict {
                        lookahead,
                        rule1: (ruleid1, production_rule1),
                        rule2: (ruleid2, production_rule2),
                    } => {
                        let mut labels = Vec::new();

                        Self::extend_rule_source_label(
                            &mut labels,
                            file_id,
                            *ruleid1,
                            &grammar,
                            "(Rule1) ",
                        );
                        Self::extend_rule_source_label(
                            &mut labels,
                            file_id,
                            *ruleid2,
                            &grammar,
                            "(Rule2) ",
                        );

                        Diagnostic::error()
                            .with_message(format!(
                                "Reduce/Reduce conflict:\n>>> {}\n>>> {}",
                                production_rule1, production_rule2
                            ))
                            .with_labels(labels)
                            .with_notes(vec![format!("with lookahead {}", lookahead)])
                    }

                    _ => {
                        let message = e.short_message();
                        let span = e.span().byte_range();
                        Diagnostic::error()
                            .with_message(message)
                            .with_labels(vec![
                                Label::primary(file_id, span).with_message("occured here")
                            ])
                    }
                };

                let writer = StandardStream::stderr(ColorChoice::Auto);
                let config = codespan_reporting::term::Config::default();
                term::emit(&mut writer.lock(), &config, &files, &diag)
                    .expect("Failed to write to stderr");

                return Err(diag.message);
            }
        };

        // this comments will be printed to the output file
        // build again here whether it was built before
        // since many informations are removed in the rusty_lr_parser output
        let mut debug_comments = String::new();
        {
            // to map production rule to its pretty name abbreviation
            let term_mapper = |term_idx: usize| grammar.terminals[term_idx].name.to_string();
            let nonterm_mapper = |nonterm: usize| grammar.nonterminals[nonterm].pretty_name.clone();

            let mut builder = grammar.create_grammar();
            debug_comments.push_str(format!("{:=^80}\n", "Grammar").as_str());
            for (rule, _) in builder.rules.iter() {
                debug_comments.push_str(
                    format!("{}\n", rule.clone().map(term_mapper, nonterm_mapper)).as_str(),
                );
            }
            let augmented_rule_id = *grammar
                .nonterminals_index
                .get(&Ident::new(
                    rusty_lr_parser::utils::AUGMENTED_NAME,
                    Span::call_site(),
                ))
                .unwrap();
            let parser = if grammar.lalr {
                match builder.build_lalr(augmented_rule_id) {
                    Ok(parser) => parser,
                    Err(_) => unreachable!("Grammar building failed"),
                }
            } else {
                match builder.build(augmented_rule_id) {
                    Ok(parser) => parser,
                    Err(_) => unreachable!("Grammar building failed"),
                }
            };

            // print note about shift/reduce conflict resolved with `%left` or `%right`
            if self.verbose_conflicts_resolving {
                for state in parser.states.iter() {
                    let mut reduce_rules = BTreeMap::new();
                    let mut shift_rules = BTreeMap::new();

                    for (shifted_rule_ref, lookaheads) in state.ruleset.rules.iter() {
                        // is end of rule, add to reduce
                        if shifted_rule_ref.shifted
                            == builder.rules[shifted_rule_ref.rule].0.rule.len()
                        {
                            for token in lookaheads.iter() {
                                reduce_rules.insert(token, shifted_rule_ref.rule);
                            }
                        }

                        // if it is not end, and next token is terminal, add to shift
                        if let Some(rusty_lr_core::Token::Term(token)) = builder.rules
                            [shifted_rule_ref.rule]
                            .0
                            .rule
                            .get(shifted_rule_ref.shifted)
                        {
                            shift_rules
                                .entry(token)
                                .or_insert_with(BTreeSet::new)
                                .insert(*shifted_rule_ref);
                        }
                    }

                    // check shift/reduce conflict
                    for (term, shift_rules) in shift_rules.into_iter() {
                        if let Some(reduce_rule) = reduce_rules.get(term) {
                            // shift/reduce conflict here
                            // since there were not error reaching here, 'term' must be set reduce_type

                            let mut message = format!(
                                "Shift/Reduce conflict with token {} was resolved:\nReduce rule:\n\t>>> {}\nShift rules:",
                                grammar.terminals[*term].name,
                                builder.rules[*reduce_rule].0.clone().map(term_mapper, nonterm_mapper)
                            );
                            for shifted_rule in shift_rules.iter() {
                                let shifted_rule = ShiftedRule {
                                    rule: builder.rules[shifted_rule.rule]
                                        .0
                                        .clone()
                                        .map(term_mapper, nonterm_mapper),
                                    shifted: shifted_rule.shifted,
                                };
                                message.push_str(format!("\n\t>>> {}", shifted_rule).as_str());
                            }

                            let mut labels = Vec::new();

                            Self::extend_rule_source_label(
                                &mut labels,
                                file_id,
                                *reduce_rule,
                                &grammar,
                                "(Reduce) ",
                            );

                            let mut shift_source_inserted = BTreeSet::new();
                            for shift_rule in shift_rules.iter() {
                                let name = &builder.rules[shift_rule.rule].0.name;
                                if !shift_source_inserted.contains(name) {
                                    shift_source_inserted.insert(name);
                                    Self::extend_rule_source_label(
                                        &mut labels,
                                        file_id,
                                        shift_rule.rule,
                                        &grammar,
                                        "(Shift) ",
                                    );
                                }
                            }

                            let term_info = &grammar.terminals[*term];
                            if let Some(reduce_type_origin) = &term_info.reduce_type {
                                let reduce_type = reduce_type_origin.reduce_type;
                                let type_string = match reduce_type {
                                    rusty_lr_core::ReduceType::Left => "%left",
                                    rusty_lr_core::ReduceType::Right => "%right",
                                };
                                for (first, last) in reduce_type_origin.sources.iter() {
                                    let range = first.byte_range().start..last.byte_range().end;
                                    labels.push(Label::primary(file_id, range).with_message(
                                        format!("Reduce type was set as {} here", type_string),
                                    ));
                                }

                                let diag =
                                    Diagnostic::note().with_message(message).with_labels(labels);

                                let writer = self.verbose_stream();
                                let config = codespan_reporting::term::Config::default();
                                term::emit(&mut writer.lock(), &config, &files, &diag)
                                    .expect("Failed to write to stderr");
                            }
                        }
                    }
                }
            }

            // print note about reduce/reduce conflict and shift/reduce conflict not resolved
            if self.verbose_conflicts {
                // to prevent duplicated messages, collect them into BTreeMap first
                let mut reduce_rules_set = BTreeMap::new();
                for state in parser.states.iter() {
                    for (term, reduce_rules) in state.reduce_map.iter() {
                        if reduce_rules.len() > 1 {
                            reduce_rules_set
                                .entry(reduce_rules)
                                .or_insert_with(BTreeSet::new)
                                .insert(term);
                        }
                    }
                }

                for (reduce_rules, terms) in reduce_rules_set.into_iter() {
                    let mut message = "Reduce/Reduce conflict:".to_string();
                    let mut labels = Vec::new();
                    let mut note = "with lookaheads: ".to_string();
                    let len = terms.len();
                    for (idx, term) in terms.into_iter().enumerate() {
                        if idx < len - 1 {
                            note.push_str(format!("{}, ", term).as_str());
                        } else {
                            note.push_str(format!("{}", term).as_str());
                        }
                    }

                    let mut reduce_source_inserted = BTreeSet::new();
                    for reduce_rule in reduce_rules.iter() {
                        message.push_str(
                            format!(
                                "\n\t>>> {}",
                                builder.rules[*reduce_rule]
                                    .0
                                    .clone()
                                    .map(term_mapper, nonterm_mapper)
                            )
                            .as_str(),
                        );
                        let name = &builder.rules[*reduce_rule].0.name;
                        if !reduce_source_inserted.contains(name) {
                            reduce_source_inserted.insert(name);
                            Self::extend_rule_source_label(
                                &mut labels,
                                file_id,
                                *reduce_rule,
                                &grammar,
                                "",
                            );
                        }
                    }

                    let diag = Diagnostic::note()
                        .with_message(message)
                        .with_labels(labels)
                        .with_notes(vec![note]);

                    let writer = self.verbose_stream();
                    let config = codespan_reporting::term::Config::default();
                    term::emit(&mut writer.lock(), &config, &files, &diag)
                        .expect("Failed to write to stderr");
                }

                let mut shift_map = BTreeMap::new();
                for state in parser.states.iter() {
                    for (term, reduce_rules) in state.reduce_map.iter() {
                        if let Some(next_state) = state.shift_goto_map_term.get(term) {
                            shift_map
                                .entry(
                                    parser.states[*next_state]
                                        .ruleset
                                        .rules
                                        .keys()
                                        .copied()
                                        .collect::<BTreeSet<_>>(),
                                )
                                .or_insert_with(BTreeSet::new)
                                .append(&mut reduce_rules.clone());
                        }
                    }
                }

                for (shift_ruleset, reduce_rules) in shift_map.into_iter() {
                    let mut message = "Shift/Reduce conflict:".to_string();
                    let mut labels = Vec::new();

                    let mut reduce_source_inserted = BTreeSet::new();
                    message.push_str("\nReduce rules:");
                    for reduce_rule in reduce_rules.iter() {
                        message.push_str(
                            format!(
                                "\n\t>>> {}",
                                builder.rules[*reduce_rule]
                                    .0
                                    .clone()
                                    .map(term_mapper, nonterm_mapper)
                            )
                            .as_str(),
                        );
                        let name = &builder.rules[*reduce_rule].0.name;
                        if !reduce_source_inserted.contains(name) {
                            reduce_source_inserted.insert(name);
                            Self::extend_rule_source_label(
                                &mut labels,
                                file_id,
                                *reduce_rule,
                                &grammar,
                                "(Reduce) ",
                            );
                        }
                    }

                    let mut shift_source_inserted = BTreeSet::new();
                    message.push_str("\nShift rules:");
                    for shifted_rule in shift_ruleset.into_iter() {
                        let shifted_rule_ = ShiftedRule {
                            rule: builder.rules[shifted_rule.rule]
                                .0
                                .clone()
                                .map(term_mapper, nonterm_mapper),
                            shifted: shifted_rule.shifted,
                        };
                        message.push_str(format!("\n\t>>> {}", shifted_rule_).as_str());

                        let name = &builder.rules[shifted_rule.rule].0.name;

                        if !shift_source_inserted.contains(name) {
                            shift_source_inserted.insert(name);
                            Self::extend_rule_source_label(
                                &mut labels,
                                file_id,
                                shifted_rule.rule,
                                &grammar,
                                "(Shift) ",
                            );
                        }
                    }

                    let diag = Diagnostic::note().with_message(message).with_labels(labels);

                    let writer = self.verbose_stream();
                    let config = codespan_reporting::term::Config::default();
                    term::emit(&mut writer.lock(), &config, &files, &diag)
                        .expect("Failed to write to stderr");
                }
            }
        }

        Ok(output::Output {
            user_stream: output_stream,
            generated_stream: expanded_stream,
            debug_comments,
        })
    }
}