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Merge pull request #12057 from hdost/add-parser-documentation

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promql: Add a Makefile target for goyacc
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Julien Pivotto 2023-03-06 11:58:41 +01:00 committed by GitHub
parent d2f5fdd17e ba1918b6d3
commit 631c2e9381
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3
.gitignore vendored
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@ -28,3 +28,6 @@ npm_licenses.tar.bz2
/.build
/**/node_modules
# Ignore parser debug
y.output

17
CONTRIBUTING.md
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@ -78,3 +78,20 @@ GO111MODULE=on go mod tidy
```
You have to commit the changes to `go.mod` and `go.sum` before submitting the pull request.
## Working with the PromQL parser
The PromQL parser grammar is located in `promql/parser/generated_parser.y` and it can be built using `make parser`.
The parser is built using [goyacc](https://pkg.go.dev/golang.org/x/tools/cmd/goyacc)
If doing some sort of debugging, then it is possible to add some verbose output. After generating the parser, then you
can modify the the `./promql/parser/generated_parser.y.go` manually.
```golang
// As of writing this was somewhere around line 600.
var (
yyDebug = 0 // This can be be a number 0 -> 5.
yyErrorVerbose = false // This can be set to true.
)
```

11
Makefile
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@ -78,6 +78,17 @@ assets-tarball: assets
@echo '>> packaging assets'
scripts/package_assets.sh
# We only want to generate the parser when there's changes to the grammar.
.PHONY: parser
parser:
@echo ">> running goyacc to generate the .go file."
ifeq (, $(shell which goyacc))
@echo "goyacc not installed so skipping"
@echo "To install: go install golang.org/x/tools/cmd/goyacc@v0.6.0"
else
goyacc -o promql/parser/generated_parser.y.go promql/parser/generated_parser.y
endif
.PHONY: test
# If we only want to only test go code we have to change the test target
# which is called by all.