Change the signature of `World::main` (#4531)

Co-authored-by: Laurenz <laurmaedje@gmail.com>

9 files changed, 97 insertions, 87 deletions

diff --git a/crates/typst-cli/src/compile.rs b/crates/typst-cli/src/compile.rs
index 4b87c3bd..d1526425 100644
--- a/crates/typst-cli/src/compile.rs
+++ b/crates/typst-cli/src/compile.rs
@@ -5,16 +5,16 @@ use std::path::{Path, PathBuf};
 use chrono::{Datelike, Timelike};
 use codespan_reporting::diagnostic::{Diagnostic, Label};
 use codespan_reporting::term;
-use ecow::{eco_format, eco_vec, EcoString, EcoVec};
+use ecow::{eco_format, EcoString};
 use parking_lot::RwLock;
 use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
-use typst::diag::{bail, FileError, Severity, SourceDiagnostic, StrResult, Warned};
+use typst::diag::{bail, Severity, SourceDiagnostic, StrResult, Warned};
 use typst::foundations::{Datetime, Smart};
 use typst::layout::{Frame, PageRanges};
 use typst::model::Document;
 use typst::syntax::{FileId, Source, Span};
 use typst::visualize::Color;
-use typst::{World, WorldExt};
+use typst::WorldExt;
 
 use crate::args::{
     CompileCommand, DiagnosticFormat, Input, Output, OutputFormat, PageRangeArgument,
@@ -96,21 +96,6 @@ pub fn compile_once(
         Status::Compiling.print(command).unwrap();
     }
 
-    if let Err(errors) = world
-        .source(world.main())
-        .map_err(|err| hint_invalid_main_file(err, &command.common.input))
-    {
-        set_failed();
-        if watching {
-            Status::Error.print(command).unwrap();
-        }
-
-        print_diagnostics(world, &errors, &[], command.common.diagnostic_format)
-            .map_err(|err| eco_format!("failed to print diagnostics ({err})"))?;
-
-        return Ok(());
-    }
-
     let Warned { output, warnings } = typst::compile(world);
 
     match output {
@@ -498,52 +483,6 @@ fn open_file(open: Option<&str>, path: &Path) -> StrResult<()> {
     }
 }
 
-/// Adds useful hints when the main source file couldn't be read
-/// and returns the final diagnostic.
-fn hint_invalid_main_file(
-    file_error: FileError,
-    input: &Input,
-) -> EcoVec<SourceDiagnostic> {
-    let is_utf8_error = matches!(file_error, FileError::InvalidUtf8);
-    let mut diagnostic =
-        SourceDiagnostic::error(Span::detached(), EcoString::from(file_error));
-
-    // Attempt to provide helpful hints for UTF-8 errors.
-    // Perhaps the user mistyped the filename.
-    // For example, they could have written "file.pdf" instead of
-    // "file.typ".
-    if is_utf8_error {
-        if let Input::Path(path) = input {
-            let extension = path.extension();
-            if extension.is_some_and(|extension| extension == "typ") {
-                // No hints if the file is already a .typ file.
-                // The file is indeed just invalid.
-                return eco_vec![diagnostic];
-            }
-
-            match extension {
-                Some(extension) => {
-                    diagnostic.hint(eco_format!(
-                        "a file with the `.{}` extension is not usually a Typst file",
-                        extension.to_string_lossy()
-                    ));
-                }
-
-                None => {
-                    diagnostic
-                        .hint("a file without an extension is not usually a Typst file");
-                }
-            };
-
-            if path.with_extension("typ").exists() {
-                diagnostic.hint("check if you meant to use the `.typ` extension instead");
-            }
-        }
-    }
-
-    eco_vec![diagnostic]
-}
-
 /// Print diagnostic messages to the terminal.
 pub fn print_diagnostics(
     world: &SystemWorld,
diff --git a/crates/typst-cli/src/world.rs b/crates/typst-cli/src/world.rs
index 8e8b305f..5a0814a8 100644
--- a/crates/typst-cli/src/world.rs
+++ b/crates/typst-cli/src/world.rs
@@ -192,8 +192,8 @@ impl World for SystemWorld {
         &self.book
     }
 
-    fn main(&self) -> Source {
-        self.source(self.main).unwrap()
+    fn main(&self) -> FileId {
+        self.main
     }
 
     fn source(&self, id: FileId) -> FileResult<Source> {
diff --git a/crates/typst-ide/src/lib.rs b/crates/typst-ide/src/lib.rs
index c4a88085..403a36ba 100644
--- a/crates/typst-ide/src/lib.rs
+++ b/crates/typst-ide/src/lib.rs
@@ -139,8 +139,8 @@ mod tests {
             &self.base.book
         }
 
-        fn main(&self) -> Source {
-            self.main.clone()
+        fn main(&self) -> FileId {
+            self.main.id()
         }
 
         fn source(&self, id: FileId) -> FileResult<Source> {
diff --git a/crates/typst-syntax/src/file.rs b/crates/typst-syntax/src/file.rs
index 356337f3..89aaa55e 100644
--- a/crates/typst-syntax/src/file.rs
+++ b/crates/typst-syntax/src/file.rs
@@ -91,6 +91,11 @@ impl FileId {
         Self::new(self.package().cloned(), self.vpath().join(path))
     }
 
+    /// The same file location, but with a different extension.
+    pub fn with_extension(&self, extension: &str) -> Self {
+        Self::new(self.package().cloned(), self.vpath().with_extension(extension))
+    }
+
     /// Construct from a raw number.
     pub(crate) const fn from_raw(v: u16) -> Self {
         Self(v)
diff --git a/crates/typst-syntax/src/path.rs b/crates/typst-syntax/src/path.rs
index b561128c..6c625642 100644
--- a/crates/typst-syntax/src/path.rs
+++ b/crates/typst-syntax/src/path.rs
@@ -85,6 +85,11 @@ impl VirtualPath {
             Self::new(path)
         }
     }
+
+    /// The same path, but with a different extension.
+    pub fn with_extension(&self, extension: &str) -> Self {
+        Self(self.0.with_extension(extension))
+    }
 }
 
 impl Debug for VirtualPath {
diff --git a/crates/typst/src/lib.rs b/crates/typst/src/lib.rs
index 50575d12..cfcfd757 100644
--- a/crates/typst/src/lib.rs
+++ b/crates/typst/src/lib.rs
@@ -60,10 +60,12 @@ use std::collections::HashSet;
 use std::ops::{Deref, Range};
 
 use comemo::{Track, Tracked, Validate};
-use ecow::{EcoString, EcoVec};
+use ecow::{eco_format, eco_vec, EcoString, EcoVec};
 use typst_timing::{timed, TimingScope};
 
-use crate::diag::{warning, FileResult, SourceDiagnostic, SourceResult, Warned};
+use crate::diag::{
+    warning, FileError, FileResult, SourceDiagnostic, SourceResult, Warned,
+};
 use crate::engine::{Engine, Route, Sink, Traced};
 use crate::foundations::{
     Array, Bytes, Datetime, Dict, Module, Scope, StyleChain, Styles, Value,
@@ -108,13 +110,19 @@ fn compile_inner(
     let library = world.library();
     let styles = StyleChain::new(&library.styles);
 
+    // Fetch the main source file once.
+    let main = world.main();
+    let main = world
+        .source(main)
+        .map_err(|err| hint_invalid_main_file(world, err, main))?;
+
     // First evaluate the main source file into a module.
     let content = crate::eval::eval(
         world,
         traced,
         sink.track_mut(),
         Route::default().track(),
-        &world.main(),
+        &main,
     )?
     .content();
 
@@ -203,8 +211,8 @@ pub trait World: Send + Sync {
     /// Metadata about all known fonts.
     fn book(&self) -> &LazyHash<FontBook>;
 
-    /// Access the main source file.
-    fn main(&self) -> Source;
+    /// Get the file id of the main source file.
+    fn main(&self) -> FileId;
 
     /// Try to access the specified source file.
     fn source(&self, id: FileId) -> FileResult<Source>;
@@ -246,7 +254,7 @@ macro_rules! delegate_for_ptr {
                 self.deref().book()
             }
 
-            fn main(&self) -> Source {
+            fn main(&self) -> FileId {
                 self.deref().main()
             }
 
@@ -402,3 +410,48 @@ fn prelude(global: &mut Scope) {
     global.define("horizon", Alignment::HORIZON);
     global.define("bottom", Alignment::BOTTOM);
 }
+
+/// Adds useful hints when the main source file couldn't be read
+/// and returns the final diagnostic.
+fn hint_invalid_main_file(
+    world: Tracked<dyn World + '_>,
+    file_error: FileError,
+    input: FileId,
+) -> EcoVec<SourceDiagnostic> {
+    let is_utf8_error = matches!(file_error, FileError::InvalidUtf8);
+    let mut diagnostic =
+        SourceDiagnostic::error(Span::detached(), EcoString::from(file_error));
+
+    // Attempt to provide helpful hints for UTF-8 errors. Perhaps the user
+    // mistyped the filename. For example, they could have written "file.pdf"
+    // instead of "file.typ".
+    if is_utf8_error {
+        let path = input.vpath();
+        let extension = path.as_rootless_path().extension();
+        if extension.is_some_and(|extension| extension == "typ") {
+            // No hints if the file is already a .typ file.
+            // The file is indeed just invalid.
+            return eco_vec![diagnostic];
+        }
+
+        match extension {
+            Some(extension) => {
+                diagnostic.hint(eco_format!(
+                    "a file with the `.{}` extension is not usually a Typst file",
+                    extension.to_string_lossy()
+                ));
+            }
+
+            None => {
+                diagnostic
+                    .hint("a file without an extension is not usually a Typst file");
+            }
+        };
+
+        if world.source(input.with_extension("typ")).is_ok() {
+            diagnostic.hint("check if you meant to use the `.typ` extension instead");
+        }
+    }
+
+    eco_vec![diagnostic]
+}
diff --git a/docs/src/html.rs b/docs/src/html.rs
index ab140a90..58c8e54c 100644
--- a/docs/src/html.rs
+++ b/docs/src/html.rs
@@ -6,7 +6,7 @@ use heck::{ToKebabCase, ToTitleCase};
 use pulldown_cmark as md;
 use serde::{Deserialize, Serialize};
 use typed_arena::Arena;
-use typst::diag::{FileResult, StrResult};
+use typst::diag::{FileError, FileResult, StrResult};
 use typst::foundations::{Bytes, Datetime};
 use typst::layout::{Abs, Point, Size};
 use typst::syntax::{FileId, Source, VirtualPath};
@@ -463,12 +463,16 @@ impl World for DocWorld {
         &FONTS.0
     }
 
-    fn main(&self) -> Source {
-        self.0.clone()
+    fn main(&self) -> FileId {
+        self.0.id()
     }
 
-    fn source(&self, _: FileId) -> FileResult<Source> {
-        Ok(self.0.clone())
+    fn source(&self, id: FileId) -> FileResult<Source> {
+        if id == self.0.id() {
+            Ok(self.0.clone())
+        } else {
+            Err(FileError::NotFound(id.vpath().as_rootless_path().into()))
+        }
     }
 
     fn file(&self, id: FileId) -> FileResult<Bytes> {
diff --git a/tests/fuzz/src/compile.rs b/tests/fuzz/src/compile.rs
index 98c300ce..c9536150 100644
--- a/tests/fuzz/src/compile.rs
+++ b/tests/fuzz/src/compile.rs
@@ -39,16 +39,20 @@ impl World for FuzzWorld {
         &self.book
     }
 
-    fn main(&self) -> Source {
-        self.source.clone()
+    fn main(&self) -> FileId {
+        self.source.id()
     }
 
-    fn source(&self, src: FileId) -> FileResult<Source> {
-        Err(FileError::NotFound(src.vpath().as_rootless_path().into()))
+    fn source(&self, id: FileId) -> FileResult<Source> {
+        if id == self.source.id() {
+            Ok(self.source.clone())
+        } else {
+            Err(FileError::NotFound(id.vpath().as_rootless_path().into()))
+        }
     }
 
-    fn file(&self, src: FileId) -> FileResult<Bytes> {
-        Err(FileError::NotFound(src.vpath().as_rootless_path().into()))
+    fn file(&self, id: FileId) -> FileResult<Bytes> {
+        Err(FileError::NotFound(id.vpath().as_rootless_path().into()))
     }
 
     fn font(&self, _: usize) -> Option<Font> {
diff --git a/tests/src/world.rs b/tests/src/world.rs
index ad925a53..47b77d7e 100644
--- a/tests/src/world.rs
+++ b/tests/src/world.rs
@@ -43,8 +43,8 @@ impl World for TestWorld {
         &self.base.book
     }
 
-    fn main(&self) -> Source {
-        self.main.clone()
+    fn main(&self) -> FileId {
+        self.main.id()
     }
 
     fn source(&self, id: FileId) -> FileResult<Source> {