garando_syntax2 0.1.0

//! A JSON emitter for errors.
//!
//! This works by converting errors to a simplified structural format (see the
//! structs at the start of the file) and then serialising them. These should
//! contain as much information about the error as possible.
//!
//! The format of the JSON output should be considered *unstable*. For now the
//! structs at the end of this file (Diagnostic*) specify the error format.

// FIXME spec the JSON output properly.

use crate::codemap::{CodeMap, FilePathMapping};
use crate::errors::emitter::Emitter;
use crate::errors::registry::Registry;
use crate::errors::{CodeMapper, CodeSuggestion, DiagnosticBuilder, RenderSpan, SubDiagnostic};
use crate::syntax_pos::{self, MacroBacktrace, MultiSpan, Span, SpanLabel};

use std::io::{self, Write};
use std::rc::Rc;
use std::vec;

use serde::Serialize;

pub struct JsonEmitter {
    dst: Box<dyn Write + Send>,
    registry: Option<Registry>,
    cm: Rc<dyn CodeMapper + 'static>,
}

impl JsonEmitter {
    pub fn stderr(registry: Option<Registry>, code_map: Rc<CodeMap>) -> JsonEmitter {
        JsonEmitter {
            dst: Box::new(io::stderr()),
            registry: registry,
            cm: code_map,
        }
    }

    pub fn basic() -> JsonEmitter {
        let file_path_mapping = FilePathMapping::empty();
        JsonEmitter::stderr(None, Rc::new(CodeMap::new(file_path_mapping)))
    }

    pub fn new(
        dst: Box<dyn Write + Send>,
        registry: Option<Registry>,
        code_map: Rc<CodeMap>,
    ) -> JsonEmitter {
        JsonEmitter {
            dst: dst,
            registry: registry,
            cm: code_map,
        }
    }
}

impl Emitter for JsonEmitter {
    fn emit(&mut self, db: &DiagnosticBuilder) {
        let data = Diagnostic::from_diagnostic_builder(db, self);
        if let Err(e) = serde_json::to_writer(&mut self.dst, &data) {
            panic!("failed to print diagnostics: {:?}", e);
        }
    }
}

// The following data types are provided just for serialisation.

#[derive(Serialize)]
struct Diagnostic {
    /// The primary error message.
    message: String,
    code: Option<DiagnosticCode>,
    /// "error: internal compiler error", "error", "warning", "note", "help".
    level: &'static str,
    spans: Vec<DiagnosticSpan>,
    /// Associated diagnostic messages.
    children: Vec<Diagnostic>,
    /// The message as rustc would render it. Currently this is only
    /// `Some` for "suggestions", but eventually it will include all
    /// snippets.
    rendered: Option<String>,
}

#[derive(Serialize)]
struct DiagnosticSpan {
    file_name: String,
    byte_start: u32,
    byte_end: u32,
    /// 1-based.
    line_start: usize,
    line_end: usize,
    /// 1-based, character offset.
    column_start: usize,
    column_end: usize,
    /// Is this a "primary" span -- meaning the point, or one of the points,
    /// where the error occurred?
    is_primary: bool,
    /// Source text from the start of line_start to the end of line_end.
    text: Vec<DiagnosticSpanLine>,
    /// Label that should be placed at this location (if any)
    label: Option<String>,
    /// If we are suggesting a replacement, this will contain text
    /// that should be sliced in atop this span. You may prefer to
    /// load the fully rendered version from the parent `Diagnostic`,
    /// however.
    suggested_replacement: Option<String>,
    /// Macro invocations that created the code at this span, if any.
    expansion: Option<Box<DiagnosticSpanMacroExpansion>>,
}

#[derive(Serialize)]
struct DiagnosticSpanLine {
    text: String,

    /// 1-based, character offset in self.text.
    highlight_start: usize,

    highlight_end: usize,
}

#[derive(Serialize)]
struct DiagnosticSpanMacroExpansion {
    /// span where macro was applied to generate this code; note that
    /// this may itself derive from a macro (if
    /// `span.expansion.is_some()`)
    span: DiagnosticSpan,

    /// name of macro that was applied (e.g., "foo!" or "#[derive(Eq)]")
    macro_decl_name: String,

    /// span where macro was defined (if known)
    def_site_span: Option<DiagnosticSpan>,
}

#[derive(Serialize)]
struct DiagnosticCode {
    /// The code itself.
    code: String,
    /// An explanation for the code.
    explanation: Option<&'static str>,
}

impl Diagnostic {
    fn from_diagnostic_builder(db: &DiagnosticBuilder, je: &JsonEmitter) -> Diagnostic {
        let sugg = db.suggestions.iter().flat_map(|sugg| {
            je.render(sugg).into_iter().map(move |rendered| Diagnostic {
                message: sugg.msg.clone(),
                code: None,
                level: "help",
                spans: DiagnosticSpan::from_suggestion(sugg, je),
                children: vec![],
                rendered: Some(rendered),
            })
        });
        Diagnostic {
            message: db.message(),
            code: DiagnosticCode::map_opt_string(db.code.clone(), je),
            level: db.level.to_str(),
            spans: DiagnosticSpan::from_multispan(&db.span, je),
            children: db
                .children
                .iter()
                .map(|c| Diagnostic::from_sub_diagnostic(c, je))
                .chain(sugg)
                .collect(),
            rendered: None,
        }
    }

    fn from_sub_diagnostic(db: &SubDiagnostic, je: &JsonEmitter) -> Diagnostic {
        Diagnostic {
            message: db.message(),
            code: None,
            level: db.level.to_str(),
            spans: db
                .render_span
                .as_ref()
                .map(|sp| DiagnosticSpan::from_render_span(sp, je))
                .unwrap_or_else(|| DiagnosticSpan::from_multispan(&db.span, je)),
            children: vec![],
            rendered: None,
        }
    }
}

impl DiagnosticSpan {
    fn from_span_label(
        span: SpanLabel,
        suggestion: Option<&String>,
        je: &JsonEmitter,
    ) -> DiagnosticSpan {
        Self::from_span_etc(span.span, span.is_primary, span.label, suggestion, je)
    }

    fn from_span_etc(
        span: Span,
        is_primary: bool,
        label: Option<String>,
        suggestion: Option<&String>,
        je: &JsonEmitter,
    ) -> DiagnosticSpan {
        // obtain the full backtrace from the `macro_backtrace`
        // helper; in some ways, it'd be better to expand the
        // backtrace ourselves, but the `macro_backtrace` helper makes
        // some decision, such as dropping some frames, and I don't
        // want to duplicate that logic here.
        let backtrace = span.macro_backtrace().into_iter();
        DiagnosticSpan::from_span_full(span, is_primary, label, suggestion, backtrace, je)
    }

    fn from_span_full(
        span: Span,
        is_primary: bool,
        label: Option<String>,
        suggestion: Option<&String>,
        mut backtrace: vec::IntoIter<MacroBacktrace>,
        je: &JsonEmitter,
    ) -> DiagnosticSpan {
        let start = je.cm.lookup_char_pos(span.lo);
        let end = je.cm.lookup_char_pos(span.hi);
        let backtrace_step = backtrace.next().map(|bt| {
            let call_site = Self::from_span_full(bt.call_site, false, None, None, backtrace, je);
            let def_site_span = bt
                .def_site_span
                .map(|sp| Self::from_span_full(sp, false, None, None, vec![].into_iter(), je));
            Box::new(DiagnosticSpanMacroExpansion {
                span: call_site,
                macro_decl_name: bt.macro_decl_name,
                def_site_span: def_site_span,
            })
        });
        DiagnosticSpan {
            file_name: start.file.name.clone(),
            byte_start: span.lo.0,
            byte_end: span.hi.0,
            line_start: start.line,
            line_end: end.line,
            column_start: start.col.0 + 1,
            column_end: end.col.0 + 1,
            is_primary: is_primary,
            text: DiagnosticSpanLine::from_span(span, je),
            suggested_replacement: suggestion.cloned(),
            expansion: backtrace_step,
            label: label,
        }
    }

    fn from_multispan(msp: &MultiSpan, je: &JsonEmitter) -> Vec<DiagnosticSpan> {
        msp.span_labels()
            .into_iter()
            .map(|span_str| Self::from_span_label(span_str, None, je))
            .collect()
    }

    fn from_suggestion(suggestion: &CodeSuggestion, je: &JsonEmitter) -> Vec<DiagnosticSpan> {
        suggestion
            .substitution_parts
            .iter()
            .flat_map(|substitution| {
                substitution.substitutions.iter().map(move |suggestion| {
                    let span_label = SpanLabel {
                        span: substitution.span,
                        is_primary: true,
                        label: None,
                    };
                    DiagnosticSpan::from_span_label(span_label, Some(suggestion), je)
                })
            })
            .collect()
    }

    fn from_render_span(rsp: &RenderSpan, je: &JsonEmitter) -> Vec<DiagnosticSpan> {
        match *rsp {
            RenderSpan::FullSpan(ref msp) => DiagnosticSpan::from_multispan(msp, je),
            // regular diagnostics don't produce this anymore
            // FIXME(oli_obk): remove it entirely
            RenderSpan::Suggestion(_) => unreachable!(),
        }
    }
}

impl DiagnosticSpanLine {
    fn line_from_filemap(
        fm: &syntax_pos::FileMap,
        index: usize,
        h_start: usize,
        h_end: usize,
    ) -> DiagnosticSpanLine {
        DiagnosticSpanLine {
            text: fm.get_line(index).unwrap_or("").to_owned(),
            highlight_start: h_start,
            highlight_end: h_end,
        }
    }

    /// Create a list of DiagnosticSpanLines from span - each line with any part
    /// of `span` gets a DiagnosticSpanLine, with the highlight indicating the
    /// `span` within the line.
    fn from_span(span: Span, je: &JsonEmitter) -> Vec<DiagnosticSpanLine> {
        je.cm
            .span_to_lines(span)
            .map(|lines| {
                let fm = &*lines.file;
                lines
                    .lines
                    .iter()
                    .map(|line| {
                        DiagnosticSpanLine::line_from_filemap(
                            fm,
                            line.line_index,
                            line.start_col.0 + 1,
                            line.end_col.0 + 1,
                        )
                    })
                    .collect()
            })
            .unwrap_or_else(|_| vec![])
    }
}

impl DiagnosticCode {
    fn map_opt_string(s: Option<String>, je: &JsonEmitter) -> Option<DiagnosticCode> {
        s.map(|s| {
            let explanation = je
                .registry
                .as_ref()
                .and_then(|registry| registry.find_description(&s));

            DiagnosticCode {
                code: s,
                explanation: explanation,
            }
        })
    }
}

impl JsonEmitter {
    fn render(&self, suggestion: &CodeSuggestion) -> Vec<String> {
        suggestion.splice_lines(&*self.cm)
    }
}