tree-sitter-sas

A tree-sitter grammar for the SAS programming language.

Node bindings

Available on npm as tree-sitter-sas.

npm install tree-sitter-sas

Prebuilt native binaries ship for linux-x64, darwin-x64, and darwin-arm64 — no compile step required.

Rust bindings

Available on crates.io as tree-sitter-sas.

[dependencies]
tree-sitter-sas = "0.3"

Python bindings

Available on PyPI as tree-sitter-sas.

pip install tree-sitter-sas

Go bindings

import "github.com/ix-infrastructure/tree-sitter-sas/bindings/go"

Swift bindings

Add to Package.swift:

.package(url: "https://github.com/ix-infrastructure/tree-sitter-sas", from: "0.3.1")

Architecture

flowchart LR
    subgraph source ["Grammar source"]
        G["grammar.js\n(tree-sitter DSL)"]
        SC["src/scanner.c\n(external scanner)"]
    end

    GEN(["tree-sitter generate"])

    subgraph generated ["Generated parser"]
        PC["src/parser.c"]
        NT["src/node-types.json"]
    end

    subgraph queries ["Queries"]
        HL["queries/highlights.scm\n(syntax highlighting)"]
        TG["queries/tags.scm\n(symbol index)"]
    end

    subgraph bindings ["Language bindings"]
        N["Node · npm"]
        R["Rust · crates.io"]
        PY["Python · PyPI"]
        GO["Go"]
        SW["Swift"]
    end

    G & SC --> GEN --> PC & NT
    NT -.-> HL & TG
    PC --> N & R & PY & GO & SW

Loading

grammar.js defines the language using the tree-sitter DSL. src/scanner.c is an external lexer that disambiguates %-prefixed macro keywords (%let, %macro, %mend, %include) from user-defined macro calls — it emits a keyword token only when the keyword is not immediately followed by an identifier character, so %letput and %macroFoo correctly fall through to macro_call_statement instead. Running tree-sitter generate produces the LR parser (src/parser.c) and the node type schema (src/node-types.json).

Language coverage

Construct	Node type
DATA step	data_step
PROC step	proc_step
%MACRO / %MEND definition	macro_definition
%name(args) call statement	macro_call_statement
%name(args) inline call	macro_call
%LET var = value	macro_variable_assignment
&var, &&var, &var. references	macro_variable_ref
%INCLUDE 'path'	include_statement
LIBNAME libref ...	libname_statement
OPTIONS ...	options_statement
/* ... */ block comments	block_comment
* ... ; line comments	line_comment
%* ... ; macro comments	percent_comment
Everything else	generic_statement (flat fallback)

Statements not matched by a specific rule are absorbed by generic_statement, which preserves the source text without losing parse continuity. The tree is always complete — unknown or proc-specific syntax never breaks the parse.

Known deviations

generic_statement as a catch-all

SAS has hundreds of proc-specific statements (MODEL, CLASS, OUTPUT inside PROC REG, etc.) that would require individual rules to represent structurally. This grammar uses generic_statement as a flat fallback for any semicolon-terminated statement not matched by a more specific rule. The tradeoff: internal proc statement structure is not captured in the tree, but the tree is always well-formed and the surrounding program structure is always intact.

Macro keyword disambiguation via external scanner

%KEYWORD tokens share a prefix with user-defined macro calls. The external scanner in src/scanner.c resolves the ambiguity: it emits a structured keyword token only when the keyword is not immediately followed by [A-Za-z0-9_]. This means %letput is a macro call, not a %let statement — matching SAS's own behavior.

Bare % in non-macro contexts

A literal % can appear in non-macro positions (e.g. width=20% in ODS style attributes). The external scanner emits a _bare_pct token for these cases, which is absorbed into generic_statement content without triggering a macro parse path.

References

• SAS Macro Language Reference
• SAS Language Reference: Concepts
• tree-sitter documentation