1 files changed, 764 insertions, 0 deletions

diff --git a/src/parser/clang/parsing.rs b/src/parser/clang/parsing.rs
new file mode 100644
index 0000000..a654681
--- /dev/null
+++ b/src/parser/clang/parsing.rs
@@ -0,0 +1,764 @@
+use super::config::Config;
+use super::entities::*;
+use crate::types::*;
+
+use anyhow::{anyhow, Context, Error, Result};
+use clang::{Clang, CompilationDatabase, Index, TranslationUnit, Usr};
+use codemap::CodeMap;
+use thiserror::Error;
+
+use std::collections::BTreeMap;
+use std::convert::{TryFrom, TryInto};
+use std::path::{Path, PathBuf};
+
+#[derive(Debug, Default)]
+struct TopLevel {
+    namespaces: BTreeMap<Usr, Described<Namespace>>,
+    variables: BTreeMap<Usr, Described<Variable>>,
+    structs: BTreeMap<Usr, Described<Struct>>,
+    functions: BTreeMap<Usr, Described<Function>>,
+}
+
+/*
+enum TopLevelEntry<'a, T> {
+    Vacant {
+        parent: &'a mut Described<Namespace>,
+    },
+    /// Vacant, but no semantic parent
+    TopLevel,
+    Occupied {
+        entity: &'a mut Described<T>,
+    },
+    Error,
+}
+*/
+
+impl TopLevel {
+    // Somehow has a lifetime issue I can't get my head around
+    /*
+    fn entry<'a, T>(&'a mut self, path: &::clang::Entity) -> Result<TopLevelEntry<'a, T>>
+    where
+        T: ClangEntity + FromNamespaceParent + FromTopLevel,
+    {
+        let usr = path.get_usr().ok_or_else(|| anyhow!("no usr"))?;
+        if let Some(parent_path) = parent(&path) {
+            let parent_entry = self.entry::<Namespace>(&parent_path)?;
+            if let TopLevelEntry::Occupied {
+                entity: namespace_parent,
+            } = parent_entry
+            {
+                Ok(match T::from_namespace_parent(namespace_parent, &usr) {
+                    None => TopLevelEntry::Vacant {
+                        parent: namespace_parent,
+                    },
+                    Some(entity) => TopLevelEntry::Occupied { entity },
+                })
+            } else {
+                panic!("Wut");
+            }
+        } else {
+            Ok(match T::from_toplevel(self, &usr) {
+                Some(entity) => TopLevelEntry::Occupied { entity },
+                None => TopLevelEntry::TopLevel,
+            })
+        }
+    }
+    */
+
+    fn get_entity_mut(&mut self, path: clang::Entity) -> Option<&mut dyn ClangEntity> {
+        let usr = path.get_usr()?;
+        if let Some(parent_path) = parent(path) {
+            let parent = self.get_entity_mut(parent_path)?;
+            Some(match path.get_kind().try_into().ok()? {
+                ClangEntityKind::Namespace => {
+                    &mut parent.get_member_namespaces()?.get_mut(&usr)?.entity
+                }
+                ClangEntityKind::Variable(_) => {
+                    &mut parent.get_member_variables()?.get_mut(&usr)?.entity
+                }
+                ClangEntityKind::Function(_) => {
+                    &mut parent.get_member_functions()?.get_mut(&usr)?.entity
+                }
+                ClangEntityKind::Struct(_) => {
+                    &mut parent.get_member_structs()?.get_mut(&usr)?.entity
+                }
+            })
+        } else {
+            Some(match path.get_kind().try_into().ok()? {
+                ClangEntityKind::Namespace => &mut self.namespaces.get_mut(&usr)?.entity,
+                ClangEntityKind::Variable(_) => &mut self.variables.get_mut(&usr)?.entity,
+                ClangEntityKind::Struct(_) => &mut self.structs.get_mut(&usr)?.entity,
+                ClangEntityKind::Function(_) => &mut self.functions.get_mut(&usr)?.entity,
+            })
+        }
+    }
+
+    fn get_namespace_mut(&mut self, path: clang::Entity) -> Option<&mut Described<Namespace>> {
+        let usr = path.get_usr()?;
+
+        if let Some(parent_path) = parent(path) {
+            let parent = self.get_entity_mut(parent_path)?;
+            parent.get_member_namespaces()?.get_mut(&usr)
+        } else {
+            self.namespaces.get_mut(&usr)
+        }
+    }
+
+    fn insert<T>(&mut self, path: clang::Entity, entity: Described<T>) -> Result<()>
+    where
+        T: ClangEntity + std::fmt::Debug,
+        Self: TopLevelManipulation<T>,
+        Namespace: NamespaceParentManipulation<T>,
+    {
+        let usr = path.get_usr().ok_or_else(|| anyhow!("no usr"))?;
+        if let Some(parent_path) = parent(path) {
+            if let Some(parent_namespace) = self.get_namespace_mut(parent_path) {
+                parent_namespace
+                    .entity
+                    .get_members_mut()
+                    // Namespace should be able to contain every kind of entity
+                    .unwrap()
+                    .insert(usr, entity);
+                Ok(())
+            } else {
+                Err(anyhow!("has parent but no parent in tree"))
+            }
+        } else {
+            self.insert_toplevel(usr, entity);
+            Ok(())
+        }
+    }
+}
+
+// Like .get_semantic_parent(), but return none if the parent is the translation unit
+fn parent(libclang_entity: clang::Entity) -> Option<clang::Entity> {
+    match libclang_entity.get_semantic_parent() {
+        Some(parent) => {
+            if parent.get_kind() != clang::EntityKind::TranslationUnit {
+                Some(parent)
+            } else {
+                None
+            }
+        }
+        None => {
+            warn!("get_semantic_parent() returned None");
+            None
+        }
+    }
+}
+
+trait TopLevelManipulation<T: ClangEntity> {
+    fn insert_toplevel(&mut self, usr: Usr, entity: Described<T>);
+}
+
+impl TopLevelManipulation<Namespace> for TopLevel {
+    fn insert_toplevel(&mut self, usr: Usr, entity: Described<Namespace>) {
+        self.namespaces.insert(usr, entity);
+    }
+}
+
+impl TopLevelManipulation<Variable> for TopLevel {
+    fn insert_toplevel(&mut self, usr: Usr, entity: Described<Variable>) {
+        self.variables.insert(usr, entity);
+    }
+}
+
+impl TopLevelManipulation<Function> for TopLevel {
+    fn insert_toplevel(&mut self, usr: Usr, entity: Described<Function>) {
+        self.functions.insert(usr, entity);
+    }
+}
+
+impl TopLevelManipulation<Struct> for TopLevel {
+    fn insert_toplevel(&mut self, usr: Usr, entity: Described<Struct>) {
+        self.structs.insert(usr, entity);
+    }
+}
+
+/*
+trait FromTopLevel: ClangEntity + Sized {
+    fn from_toplevel<'a>(toplevel: &'a mut TopLevel, usr: &Usr) -> Option<&'a mut Described<Self>>;
+}
+
+impl FromTopLevel for Namespace {
+    fn from_toplevel<'a>(toplevel: &'a mut TopLevel, usr: &Usr) -> Option<&'a mut Described<Self>> {
+        toplevel.namespaces.get_mut(usr)
+    }
+}
+
+impl FromTopLevel for Variable {
+    fn from_toplevel<'a>(toplevel: &'a mut TopLevel, usr: &Usr) -> Option<&'a mut Described<Self>> {
+        toplevel.variables.get_mut(usr)
+    }
+}
+
+impl FromTopLevel for Function {
+    fn from_toplevel<'a>(toplevel: &'a mut TopLevel, usr: &Usr) -> Option<&'a mut Described<Self>> {
+        toplevel.functions.get_mut(usr)
+    }
+}
+
+impl FromTopLevel for Struct {
+    fn from_toplevel<'a>(toplevel: &'a mut TopLevel, usr: &Usr) -> Option<&'a mut Described<Self>> {
+        toplevel.structs.get_mut(usr)
+    }
+}
+*/
+
+pub(crate) fn parse_compile_commands(
+    config: &Config,
+    codemap: &mut CodeMap,
+) -> Result<BTreeMap<EntityId, Entity>> {
+    let clang = Clang::new().unwrap();
+    let index = Index::new(
+        &clang, /* exclude from pch = */ false, /* print diagnostics = */ false,
+    );
+
+    debug!("Extra libclang argument: {:?}", config.extra_args);
+
+    debug!(
+        "Loading compile commands from: {:?}",
+        config.compile_commands_location
+    );
+    let database =
+        CompilationDatabase::from_directory(&config.compile_commands_location).map_err(|()| {
+            CompileCommandsLoadError {
+                path: config.compile_commands_location.clone(),
+            }
+        })?;
+
+    let toplevel_directory = std::env::current_dir().context("Cannot read current directory")?;
+
+    let mut entities = TopLevel::default();
+
+    for command in database.get_all_compile_commands().get_commands() {
+        let directory = command.get_directory();
+        trace!("Changing directory to: {:?}", directory);
+        std::env::set_current_dir(&directory)
+            .with_context(|| format!("Cannot change current directory to: {:?}", directory))?;
+
+        let filename = command.get_filename();
+
+        let file_map = codemap.add_file(
+            filename
+                .to_str()
+                .context("File is not valid UTF-8")?
+                .to_owned(),
+            std::fs::read_to_string(&filename)
+                .with_context(|| format!("Cannot readfile: {:?}", filename))?,
+        );
+
+        trace!("Parsing file: {:?}", filename);
+        // The file name is passed as an argument in the compile commands
+        let mut parser = index.parser("");
+        parser.skip_function_bodies(true);
+
+        let mut clang_arguments = command.get_arguments();
+        clang_arguments.extend_from_slice(&config.extra_args);
+        trace!("Parsing with libclang arguments: {:?}", clang_arguments);
+        parser.arguments(&clang_arguments);
+
+        parse_unit(
+            &parser
+                .parse()
+                .with_context(|| format!("Could not parse file: {:?}", filename))?,
+            &mut entities,
+            &toplevel_directory,
+            file_map.span,
+            &codemap,
+        )?;
+
+        trace!("Changing directory to: {:?}", directory);
+        std::env::set_current_dir(&toplevel_directory).with_context(|| {
+            format!(
+                "Cannot change current directory to: {:?}",
+                toplevel_directory
+            )
+        })?;
+    }
+
+    let normalized_entities = entities
+        .namespaces
+        .into_iter()
+        .map(|(usr, entity)| (EntityId(usr.0), entity.into()))
+        .chain(
+            entities
+                .variables
+                .into_iter()
+                .map(|(usr, entity)| (EntityId(usr.0), entity.into())),
+        )
+        .chain(
+            entities
+                .structs
+                .into_iter()
+                .map(|(usr, entity)| (EntityId(usr.0), entity.into())),
+        )
+        .chain(
+            entities
+                .functions
+                .into_iter()
+                .map(|(usr, entity)| (EntityId(usr.0), entity.into())),
+        )
+        .collect();
+
+    Ok(normalized_entities)
+}
+
+/*
+pub(crate) fn parse_file<T, S>(path: T, extra_args: &[S]) -> EntitiesManager
+where
+    T: Into<PathBuf>,
+    T: AsRef<Path>,
+    T: ToString,
+    S: AsRef<str>,
+    S: std::fmt::Debug,
+{
+    let mut codemap = CodeMap::new();
+    let file_map = codemap.add_file(path.to_string(), std::fs::read_to_string(&path).unwrap());
+    let file_span = file_map.span;
+
+    let clang = Clang::new().unwrap();
+    let index = Index::new(&clang, true, false);
+    let mut parser = index.parser(path);
+    parser.skip_function_bodies(true);
+
+    parser.arguments(&extra_args);
+
+    if log_enabled!(log::Level::Debug) {
+        for extra_arg in extra_args {
+            debug!("Extra libclang argument: {:?}", extra_arg);
+        }
+    }
+
+    let trans_unit = parser.parse().unwrap();
+    let mut entities = EntitiesManager::new();
+
+    parse_unit(
+        &trans_unit,
+        &mut entities,
+        &std::env::current_dir().unwrap(),
+        file_span,
+        &codemap,
+    )
+    .unwrap();
+
+    entities
+}
+*/
+
+fn parse_unit(
+    trans_unit: &TranslationUnit,
+    entities: &mut TopLevel,
+    base_dir: impl AsRef<Path>,
+    file_span: codemap::Span,
+    codemap: &CodeMap,
+) -> Result<()> {
+    trans_unit.get_entity().visit_children(|entity, _parent| {
+        if is_in_system_header(entity, &base_dir) {
+            trace!(
+                "Entity is in system header, skipping: USR = {:?}",
+                entity.get_display_name()
+            );
+            return clang::EntityVisitResult::Continue;
+        }
+
+        // TODO: wrap this callback in another function so that we can use the
+        // "?" operator instead of all these `match`es
+        let usr = match entity.get_usr() {
+            Some(usr) => usr,
+            None => return clang::EntityVisitResult::Continue,
+        };
+        trace!("Entity with USR = {:?}", usr);
+        debug!("Parsing toplevel entity: {:?}", entity);
+
+        add_entity(entity, entities, file_span, codemap)
+    });
+
+    /*
+    use codemap_diagnostic::{ColorConfig, Emitter};
+
+    let mut emitter = Emitter::stderr(ColorConfig::Auto, Some(&codemap));
+
+    for diagnostic in trans_unit.get_diagnostics().iter() {
+        let main_diag = match clang_diag_to_codemap_diag(&diagnostic, file_span) {
+            Some(diag) => diag,
+            None => continue,
+        };
+
+        let sub_diags = diagnostic
+            .get_children()
+            .into_iter()
+            .filter_map(|diagnostic| clang_diag_to_codemap_diag(&diagnostic, file_span));
+
+        let fix_it_diags = diagnostic
+            .get_fix_its()
+            .into_iter()
+            .map(|fix_it| clang_fix_it_to_codemap_diag(&fix_it, file_span));
+
+        emitter.emit(
+            &std::iter::once(main_diag)
+                .chain(sub_diags)
+                .chain(fix_it_diags)
+                .collect::<Vec<_>>(),
+        );
+    }
+    */
+
+    Ok(())
+}
+
+fn is_in_system_header(entity: clang::Entity, base_dir: impl AsRef<Path>) -> bool {
+    if entity.is_in_system_header() {
+        true
+    } else if let Some(location) = entity.get_location() {
+        if let Some(file) = location.get_file_location().file {
+            !file
+                .get_path()
+                .canonicalize()
+                .unwrap()
+                .starts_with(base_dir)
+        } else {
+            // Not defined in a file? probably shouldn't document
+            true
+        }
+    } else {
+        // Not defined anywhere? probably shouldn't document
+        true
+    }
+}
+
+// Entries encountered in the toplevel lexical context
+fn add_entity(
+    libclang_entity: clang::Entity,
+    toplevel: &mut TopLevel,
+    file_span: codemap::Span,
+    codemap: &CodeMap,
+) -> clang::EntityVisitResult {
+    if libclang_entity.get_usr().is_none() {
+        return clang::EntityVisitResult::Continue;
+    };
+
+    let kind = match ClangEntityKind::try_from(libclang_entity.get_kind()) {
+        Ok(kind) => kind,
+        Err(err) => {
+            use codemap_diagnostic::{
+                ColorConfig, Diagnostic, Emitter, Level, SpanLabel, SpanStyle,
+            };
+            let spans = if let Some(range) = libclang_entity.get_range() {
+                // TODO: add every file parsed in this translation unit to the
+                // codemap, so we can properly report errors
+                if !range.is_in_main_file() {
+                    vec![]
+                } else {
+                    let begin = range.get_start().get_file_location().offset as u64;
+                    let end = range.get_end().get_file_location().offset as u64;
+
+                    vec![SpanLabel {
+                        span: file_span.subspan(begin, end),
+                        label: None,
+                        style: SpanStyle::Primary,
+                    }]
+                }
+            } else {
+                vec![]
+            };
+
+            let diag = Diagnostic {
+                level: Level::Warning,
+                message: format!("{}", err),
+                code: None,
+                spans,
+            };
+
+            let mut emitter = Emitter::stderr(ColorConfig::Auto, Some(codemap));
+            emitter.emit(&[diag]);
+
+            return clang::EntityVisitResult::Continue;
+        }
+    };
+
+    if let Some(in_tree_entity) = toplevel.get_entity_mut(libclang_entity) {
+        // if current.has_documentation && !tree.has_documentation {
+        //     append_documentation
+        // }
+    } else if libclang_entity.is_definition() {
+        // TODO: This probably means that you can't put documentation in forward declarations.
+        // TODO: Ad-hoc toplevel functions are not documented
+        //
+        // This seems restrictive, but since there can be multiple declarations but only one definition,
+        // you should probably put your documentation on the definition anyway?
+        //
+        // Also, skipping forward declarations allows us to not have to insert, then update the tree
+        // when we see the definition.
+
+        let result = match kind {
+            ClangEntityKind::Namespace => Described::<Namespace>::try_from(libclang_entity)
+                .and_then(|namespace| toplevel.insert(libclang_entity, namespace)),
+            ClangEntityKind::Variable(_) => Described::<Variable>::try_from(libclang_entity)
+                .and_then(|variable| toplevel.insert(libclang_entity, variable)),
+            ClangEntityKind::Struct(_) => Described::<Struct>::try_from(libclang_entity)
+                .and_then(|r#struct| toplevel.insert(libclang_entity, r#struct)),
+            ClangEntityKind::Function(_) => Described::<Function>::try_from(libclang_entity)
+                .and_then(|function| toplevel.insert(libclang_entity, function)),
+        };
+        // TODO: check result
+    }
+
+    if kind == ClangEntityKind::Namespace {
+        // Recurse here since namespace definitions are allowed to change between translation units.
+        ::clang::EntityVisitResult::Recurse
+    } else {
+        ::clang::EntityVisitResult::Continue
+    }
+}
+
+impl<'a, T> TryFrom<clang::Entity<'a>> for Described<T>
+where
+    T: TryFrom<clang::Entity<'a>, Error = Error>,
+{
+    type Error = Error;
+
+    fn try_from(entity: clang::Entity<'a>) -> Result<Self, Error> {
+        Ok(Described::<T> {
+            description: get_description(entity)?,
+            entity: T::try_from(entity)?,
+        })
+    }
+}
+
+impl<'a> TryFrom<clang::Entity<'a>> for Namespace {
+    type Error = Error;
+
+    fn try_from(entity: clang::Entity) -> Result<Self, Error> {
+        match entity.get_kind().try_into() {
+            Ok(ClangEntityKind::Namespace) => {}
+            _ => panic!("Trying to parse a non-variable into a variable"),
+        }
+        debug!("Parsing Namespace: {:?}", entity);
+
+        // Do not recurse here, but recurse in the main loop, since namespace
+        // definitions is allowed to change between translation units
+
+        Ok(Namespace {
+            member_namespaces: Default::default(),
+            member_variables: Default::default(),
+            member_structs: Default::default(),
+            member_functions: Default::default(),
+        })
+    }
+}
+
+impl<'a> TryFrom<clang::Entity<'a>> for Variable {
+    type Error = Error;
+
+    fn try_from(entity: clang::Entity) -> Result<Self, Error> {
+        let variable_kind;
+        match entity.get_kind().try_into() {
+            Ok(ClangEntityKind::Variable(kind)) => {
+                variable_kind = kind;
+            }
+            _ => panic!("Trying to parse a non-variable into a variable"),
+        }
+        debug!("Parsing Variable: {:?}", entity);
+
+        let r#type = entity.get_type().unwrap().get_display_name();
+        trace!("Variable has type: {:?}", r#type);
+
+        Ok(Variable {
+            r#type,
+            kind: variable_kind,
+        })
+    }
+}
+
+impl<'a> TryFrom<clang::Entity<'a>> for Struct {
+    type Error = Error;
+
+    fn try_from(entity: clang::Entity) -> Result<Self, Error> {
+        let struct_kind;
+        match entity.get_kind().try_into() {
+            Ok(ClangEntityKind::Struct(kind)) => {
+                struct_kind = kind;
+            }
+            _ => panic!("Trying to parse a non-class into a class"),
+        }
+        debug!("Parsing Struct: {:?}", entity);
+
+        let mut member_variables = BTreeMap::new();
+        let mut member_structs = BTreeMap::new();
+        let mut member_functions = BTreeMap::new();
+
+        for child in entity.get_children() {
+            trace!("Struct has child: {:?}", child);
+
+            match child.get_kind().try_into() {
+                Ok(ClangEntityKind::Variable(_)) => {
+                    let child_usr = child.get_usr().ok_or_else(|| anyhow!("no usr"))?;
+                    member_variables.insert(child_usr, Described::<Variable>::try_from(child)?);
+                }
+                Ok(ClangEntityKind::Struct(_)) => {
+                    let child_usr: Usr = child.get_usr().ok_or_else(|| anyhow!("no usr"))?;
+                    member_structs.insert(child_usr, Described::<Struct>::try_from(child)?);
+                }
+                Ok(ClangEntityKind::Function(_)) => {
+                    let child_usr = child.get_usr().ok_or_else(|| anyhow!("no usr"))?;
+                    member_functions.insert(child_usr, Described::<Function>::try_from(child)?);
+                }
+                _ => trace!("Skipping child"),
+            }
+        }
+
+        Ok(Struct {
+            kind: struct_kind,
+            member_functions,
+            member_structs,
+            member_variables,
+        })
+    }
+}
+
+impl<'a> TryFrom<clang::Entity<'a>> for Function {
+    type Error = Error;
+
+    fn try_from(entity: clang::Entity) -> Result<Self, Error> {
+        let function_kind;
+        match entity.get_kind().try_into() {
+            Ok(ClangEntityKind::Function(kind)) => {
+                function_kind = kind;
+            }
+            _ => panic!("Trying to parse a non-function into a function"),
+        }
+        debug!("Parsing Function: {:?}", entity);
+
+        let return_type = entity.get_result_type().unwrap().get_display_name();
+        trace!("Function has return type: {:?}", return_type);
+        let arguments = entity
+            .get_arguments()
+            .unwrap()
+            .into_iter()
+            .map(|arg| {
+                let name = arg
+                    .get_display_name()
+                    .unwrap_or_else(|| String::from("unnamed"));
+                let r#type = arg.get_type().unwrap().get_display_name();
+                trace!("Function has argument {:?} of type {:?}", name, r#type);
+                FunctionArgument { name, r#type }
+            })
+            .collect();
+
+        Ok(Function {
+            kind: function_kind,
+            arguments,
+            return_type,
+        })
+    }
+}
+
+fn get_description(entity: clang::Entity) -> Result<Description> {
+    let name = entity
+        .get_display_name()
+        .ok_or_else(|| anyhow!("Entity has no name: {:?}", entity))?;
+
+    // TODO: is that the best?
+    if let (Some(brief), Some(comment)) = (entity.get_comment_brief(), entity.get_comment()) {
+        Ok(Description {
+            name,
+            brief,
+            detailed: parse_comment(comment),
+        })
+    } else {
+        Ok(Description {
+            name,
+            brief: String::new(),
+            detailed: String::new(),
+        })
+    }
+}
+
+pub fn parse_comment(raw: String) -> String {
+    #[derive(Debug)]
+    enum CommentStyle {
+        // Comments of type `/**` or `/*!`
+        Starred,
+        // Comments of type `///`
+        SingleLine,
+    }
+
+    let mut chars = raw.chars();
+    let style = match &chars.as_str()[..3] {
+        "/*!" | "/**" => CommentStyle::Starred,
+        "///" => CommentStyle::SingleLine,
+        _ => panic!("Comment is empty or doesn't start with either `///`, `/**`, or `/*!`"),
+    };
+
+    chars.nth(2);
+
+    let mut result = String::new();
+
+    'parse_loop: loop {
+        let maybe_space = chars.next();
+        let mut empty_line = false;
+        match maybe_space {
+            // TODO: Warn on empty comments
+            None => break,
+            Some(' ') => {}
+            Some('\n') => {
+                empty_line = true;
+                result.push('\n');
+            }
+            Some(ch) => result.push(ch),
+        }
+
+        if !empty_line {
+            let rest = chars.as_str();
+            match rest.find('\n') {
+                None => {
+                    result.push_str(rest);
+                    break;
+                }
+                Some(position) => {
+                    result.push_str(&rest[..=position]);
+                    chars.nth(position);
+                }
+            }
+        }
+
+        // Beginning of the line
+        let first_non_ws_ch = 'ws_loop: loop {
+            let maybe_whitespace = chars.next();
+            match maybe_whitespace {
+                None => break 'parse_loop,
+                Some(ch) if ch.is_whitespace() => continue,
+                Some(ch) => break 'ws_loop ch,
+            }
+        };
+
+        match style {
+            CommentStyle::Starred if first_non_ws_ch == '*' => {
+                if &chars.as_str()[..1] == "/" {
+                    break;
+                }
+            }
+            CommentStyle::Starred => result.push(first_non_ws_ch),
+            CommentStyle::SingleLine => {
+                assert!(first_non_ws_ch == '/');
+                let rest = chars.as_str();
+                if &rest[..2] == "//" {
+                    chars.nth(1);
+                } else if &rest[..1] == "/" {
+                    chars.nth(0);
+                } else {
+                    panic!("Could not parse comment");
+                }
+            }
+        }
+    }
+
+    result
+}
+
+#[derive(Debug, Clone, Error)]
+#[error("Failed to load 'compile_commands.json' at path: {:?}", path)]
+pub(crate) struct CompileCommandsLoadError {
+    path: PathBuf,
+}