Error recovery for Rascal

[sungshik]

History

• A few initial commits to do a first integration of error recovery
• Debounce the parser #475
• Show skipped part and use error tree for outlining #476
• Both outline and codelenses support can now handle error trees #491
• Process parse errors (including error nodes) in TextDocumentState #492
• Simplify the debouncer and add tests #512

Building a VSIX package

Run the following script:

# Installing `rascal`
git clone https://github.com/usethesource/rascal.git
cd rascal
git checkout feat/error-recovery
mvn install -Drascal.compile.skip -Drascal.tutor.skip -DskipTests
RASCAL_VERSION=$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout)
cd ..

# Building the VSIX package
git clone https://github.com/usethesource/rascal-language-servers.git
cd rascal-language-servers/rascal-lsp
git checkout error-recovery/rascal
mvn versions:use-dep-version -Dincludes=org.rascalmpl:rascal -DdepVersion=$RASCAL_VERSION -DforceVersion=true
cd ../rascal-vscode-extension
npm ci
cd ..
./build.sh -fd
./package.sh
cd ..

# Cleaning up
mv rascal-language-servers/rascal-vscode-extension/*.vsix .
yes | rm -r rascal rascal-language-servers

[jurgenvinju]

I'm missing something here. If a node like this matches then it has enough structure to produce the symbol. What does it matter if there are errors inside?

[jurgenvinju]

The point of the error trees is that they will be there but won't match with any of the expected language constructs. So you can ignore them typically.

For the case where you encounter one during recursion, a match on the error tree has to be added that ignores it or does something useful like a short yield: "<error tree>"[..25]

[jurgenvinju]

Yield of an error tree is guaranteed to work: "<myStat>" will yield the entire string that was accepted to fill in for a real statement.