tree-sitter-irules 0.1.1

F5 iRules grammar for tree-sitter

tree-sitter-irules

A tree-sitter parser for F5 iRules — the TCL-derived scripting language used to program traffic management on F5 BIG-IP.

Repository: https://github.com/dekobon/tree-sitter-irules.

iRules are syntactically a dialect of TCL with three additions:

• Event handlers: when CLIENT_ACCEPTED { ... }, with optional priority N and timing on|off modifiers.
• Namespace-qualified built-in commands: HTTP::host, IP::client_addr, LB::server, SSL::cert, TCP::respond, etc.
• Extra expression operators on top of TCL's eq/ne/in/ni: starts_with, ends_with, contains, equals, matches, matches_regex, matches_glob.

This grammar is built as an extension of tree-sitter-tcl by Lewis Russell, redistributed under the MIT license. See LICENSE.

Recognised iRules surface

Names below come from F5's authoritative sources: Commands.html, iRulesReference.html, Operators.html, and when.html. The list reflects what queries/irules/highlights.scm will tag as @function.builtin; commands outside the list still parse, they just fall through to the generic @function capture.

Namespaced commands (<NS>::<command>):

Group	Namespaces
Transport / IP	IP, TCP, UDP, SCTP, LINK, VLAN, ROUTE, DATAGRAM, DHCP, FLOW, FLOWTABLE, IPFIX, LSN, NSH, PCP
TLS	SSL, CLIENTSSL, SERVERSSL, TLS, X509, IKE
HTTP	HTTP, HTTP2, HTTP3, WS, WEBSOCKET, CACHE, COMPRESS, REWRITE, STREAM, URI, JSON, XML, HTML, SSE
Other application	DNS, SIP, SDP, RTSP, FTP, MQTT, FIX, DIAMETER, RADIUS, ICAP, GTP, TDS, NTLM, MR, GENERICMESSAGE, CONNECTOR, DNSMSG, IMAP, POP3, SIPALG, SMTPS, SOCKS
Load balancing / virtual	LB, POOL, NODE, MEMBER, VIRTUAL, SNAT, SNATPOOL, PERSIST, PROFILE, PROXY, ONECONNECT, RATELIMIT, SCRUBBER, GTM, TMM, TMSH, BWC, ISESSION, IVS, L7CHECK
Access / security	ACL, ACCESS, ACCESS2, AAA, AUTH, WEBSSO, VDI, WAM, TAP, ASM, BOTDEFENSE, ANTIFRAUD, DOSL7, CATEGORY, CLASSIFICATION, CLASSIFY, CLASS, ADM, APM, ECA, POLICY, PSC
Adaptation / data	ADAPT, PEM, AVR, STATS, TABLE, SESSION, EVENT, LOG, LOGGING, MEMORY, RESOLV, RESOLVER, REST, XLAT, NAME, HSL, ILX, QOE, MATRIX, NS, ISTATS, MESSAGE, SIDEBAND
Crypto / encoding	CRYPTO, AES, DES, RC4, HMAC, MD5, SHA1, SHA256, SHA384, SHA512, B64, HEX, BIGNUM, ASN1

Global (non-namespaced) iRules commands also tagged as @function.builtin: accumulate, active_members, active_nodes, after, b64decode, b64encode, call, clientside, clone, collect, connect, crc32, decode_uri, discard, domain, drop, event, findclass, findstr, forward, getfield, htonl, htons, listen, matchclass, member, members, node, nodes, ntohl, ntohs, peer, persist, pool, recv, reject, release, send, serverside, session, sharedvar, snat, snatpool, substr, table, virtual.

Event names are intentionally open: anything matching /[A-Z][A-Z0-9_]*/ parses as an event_name. F5 documents 200+ events across protocol families and adds new ones each BIG-IP release; encoding a closed set in the parser would force a regen on every release. Validate event spellings in a linter, not the parser.

TCL baseline

iRules is a TCL 8.4 dialect (per F5 K6091). TCL 8.5 features (dict, lassign, ** operator, expanded lsearch switches) and TCL 8.6 features (try/on error/finally, lmap, throw) are available on BIG-IP 12.x and later when explicitly enabled. The grammar follows the tree-sitter-tcl baseline, so 8.5/8.6 syntax parses fine — but keep in mind that older BIG-IP runtimes will reject those constructs.

A subset of TCL commands is disabled at runtime in iRules for safety (exec, file, open, socket, and others; see F5's DisabledTclCommands.html). The parser does not enforce the disabled list — disabled commands parse as ordinary TCL commands. Linting/validation is out of scope here.

Known limitations

• Bare-word operands in expr contexts must be quoted or braced, as in stock TCL. if {$x eq foo} produces an (ERROR ...) node because TCL's own expr rejects unquoted barewords (invalid bareword "foo"); write if {$x eq "foo"} or if {$x eq {foo}}. $var, numbers, booleans, [cmd], and "strings" are all accepted operands.
• Plain matches operator (no _glob/_regex suffix) is accepted by the grammar but is not documented on F5's Operators page. It is retained for upstream tree-sitter-tcl compatibility; prefer matches_glob or matches_regex.

Status

Early. The grammar parses iRules as TCL plus iRules-specific event handlers and tags iRules namespace commands and globals in queries/irules/highlights.scm.

Building

git clone https://github.com/dekobon/tree-sitter-irules.git
cd tree-sitter-irules
npm install
npx tree-sitter generate
make test   # runs the suite under a memory cap; see Known limitations

The committed src/parser.c is generated by the exact tree-sitter-cli version recorded in package-lock.json and CI pins to that same version, so contributors must regenerate parser.c with the locally-installed CLI (npx tree-sitter generate) — never with a globally-installed one — when bumping tree-sitter-cli. See AGENTS.md for the full versioning, commit, and changelog conventions.

Using it

Pick the binding for your toolchain. All bindings expose tree_sitter_irules (or the language-idiomatic equivalent) and resolve to the same src/parser.c + src/scanner.c.

No release has been tagged yet, so all snippets below resolve from the default branch. Once a release vX.Y.Z is cut, swap each snippet to a pinned form: Cargo tag = "vX.Y.Z" (instead of branch = "main"), Go @vX.Y.Z (instead of @latest), npm github:dekobon/tree-sitter-irules#vX.Y.Z, pip git+https://github.com/dekobon/tree-sitter-irules@vX.Y.Z, or the published package version once available on the relevant registry.

# Cargo.toml
[dependencies]
tree-sitter-irules = { git = "https://github.com/dekobon/tree-sitter-irules", branch = "main" }

# Go: resolves to a pseudo-version of the latest commit on main.
go get github.com/dekobon/tree-sitter-irules@latest

// package.json
"dependencies": { "tree-sitter-irules": "github:dekobon/tree-sitter-irules" }

# pyproject.toml
[project]
dependencies = ["tree-sitter-irules @ git+https://github.com/dekobon/tree-sitter-irules"]

Bindings ship the parser only. Editor / runtime integrations also need to load queries/irules/highlights.scm (and optionally folds.scm / indents.scm) for highlighting and structural navigation; consult your editor's tree-sitter integration docs for how to register the queries. The Rust binding additionally re-exports the highlights query as HIGHLIGHTS_QUERY.

Filetype detection

The repo ships ftdetect/irules.lua and ftplugin/irules.lua for Neovim. The ftdetect file maps *.irule and *.irules to filetype irules unconditionally; the ftplugin then calls vim.treesitter.start() for that filetype. Highlighting only renders once the parser binary and queries/irules/highlights.scm are registered with nvim-treesitter (or equivalent) — without that, the start() call is a no-op and the buffer falls back to non-treesitter highlighting.

iRules are also commonly stored with a plain .tcl extension — we deliberately do not claim .tcl globally, since most .tcl files on disk are ordinary TCL. To opt specific .tcl files into the iRules parser, pick one of:

• Modeline at the top of the file: # vim: set filetype=irules :

• Per-project autocmd in .nvim.lua (sourced after :cd into the project via Neovim's 'exrc'). Note vim.fn.getcwd() is evaluated when the autocmd is defined, so this snippet belongs in a per-project config, not a global init.lua:

  vim.api.nvim_create_autocmd({ "BufRead", "BufNewFile" }, {
    pattern = vim.fn.getcwd() .. "/irules/*.tcl",
    callback = function() vim.bo.filetype = "irules" end,
  })
  

• Content-based detection for files that always start with a when block:

  vim.filetype.add({
    pattern = {
      [".*%.tcl$"] = function(_, bufnr)
        local first = vim.api.nvim_buf_get_lines(bufnr, 0, 1, false)[1] or ""
        if first:match("^%s*when%s+[A-Z][A-Z0-9_]*") then return "irules" end
      end,
    },
  })
  

Other editors follow the same pattern: keep .tcl mapped to TCL by default and override per-directory or via a header comment.

Layout

• grammar.js — grammar definition (TCL base + iRules when event handler).
• queries/irules/ — highlight, fold, and indent queries with iRules-aware tags.
• test/corpus/ — corpus tests (TCL tests inherited; iRules-specific tests in test/corpus/irules.txt).
• bindings/ — language bindings (C, Go, Node, Python, Rust, Swift).

Contributing

• Issues and feature requests: https://github.com/dekobon/tree-sitter-irules/issues
• Pull requests welcome. Read AGENTS.md first — it documents the Conventional Commits / SemVer / Keep-a-Changelog conventions, the validation gates (npx tree-sitter generate, make test, npm run lint), and the rule that committed src/parser.c must be generated by the tree-sitter-cli version recorded in package-lock.json.

License

MIT. See LICENSE. This grammar is a fork of tree-sitter-tcl by Lewis Russell; original copyright is retained alongside the tree-sitter-irules project copyright.