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* cleanup magefile; antlr stuff * fixed broken magefile * Tidy up grammar directory * antlr tools
38 lines
1.2 KiB
Markdown
38 lines
1.2 KiB
Markdown
# SLQ Grammar
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The query language used by `sq` is formally known as _SLQ_. The
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grammar is defined in `SLQ.g4`, which is an [ANTLR4](https://www.antlr.org/) grammar.
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There's a bunch of valid sample input in the `testdata` dir.
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The `antlr4` tool generates the parser / lexer files from the grammar.
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Being that `antlr4` is Java-based, Java must be installed to regenerate
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from the grammar. The process is encapsulated in `generate.sh` (or execute
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`go generate ./...`).
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The generated `.go` files ultimately end up in package `libsq/ast/internal/slq`. Files
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in this directory should not be directly edited.
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The `libsq/ast.Parse` function takes a `SLQ` input string and returns an `*ast.AST`.
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The entrypoint that accepts the SLQ string is `libsq.ExecuteSLQ`, which ultimately
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invokes `ast.Parse`.
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## Working with the grammar
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You probably should install the [antlr tools](https://github.com/antlr/antlr4-tools).
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```shell
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pip install antlr4-tools
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```
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You may also find [antlr4ts](https://github.com/tunnelvisionlabs/antlr4ts) useful.
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```shell
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npm install antlr4ts
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```
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And there are various [IDE plugins](https://github.com/antlr/antlr4-tools) available.
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In particular, note the [VS Code extension](https://github.com/mike-lischke/vscode-antlr4).
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