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package grammar
import (
"bufio"
"encoding/json"
"io"
"os"
"os/exec"
"strings"
"sync"
)
// binary is the harper-ls executable name; a var so tests can point it elsewhere.
var binary = "harper-ls"
// Available reports whether harper-ls is on PATH. When false, callers should skip
// grammar entirely — no subprocess, no cost.
func Available() bool {
_, err := exec.LookPath(binary)
return err == nil
}
// Client is a running harper-ls session reached over stdio. It tracks the text of
// each open document so it can translate LSP diagnostic ranges (UTF-16) into
// glint's rune columns, and publishes diagnostic batches on Diagnostics().
type Client struct {
cmd *exec.Cmd
stdin io.WriteCloser
writeMu sync.Mutex
nextID int
docMu sync.Mutex
docs map[string]docState // uri -> latest text/version
diags chan []Diag
ready chan struct{}
done chan struct{}
}
type docState struct {
version int
lines []string
}
// Start launches harper-ls, performs the LSP initialize handshake, and begins
// serving diagnostics. The returned Client is ready for DidOpen once Start
// returns. Callers should guard with Available first.
func Start() (*Client, error) {
cmd := exec.Command(binary, "--stdio")
stdin, err := cmd.StdinPipe()
if err != nil {
return nil, err
}
stdout, err := cmd.StdoutPipe()
if err != nil {
return nil, err
}
cmd.Stderr = nil // discard harper's log noise
if err := cmd.Start(); err != nil {
return nil, err
}
c := &Client{
cmd: cmd,
stdin: stdin,
docs: map[string]docState{},
diags: make(chan []Diag, 1),
ready: make(chan struct{}),
done: make(chan struct{}),
}
go c.readLoop(bufio.NewReader(stdout))
c.initialize()
return c, nil
}
// Diagnostics is the stream of diagnostic batches, one per harper
// publishDiagnostics for a tracked document, already mapped to rune columns. The
// channel is buffered depth 1 and always holds the latest batch: a slow reader
// never blocks the client, but never sees a stale batch either.
func (c *Client) Diagnostics() <-chan []Diag { return c.diags }
// DidOpen registers a document with harper and requests its first diagnostics.
func (c *Client) DidOpen(path, text string) {
uri := pathToURI(path)
c.setDoc(uri, 1, text)
c.notify("textDocument/didOpen", map[string]any{
"textDocument": map[string]any{
"uri": uri, "languageId": "markdown", "version": 1, "text": text,
},
})
}
// DidChange sends the full new text for an open document (harper uses Full sync),
// bumping its version so diagnostics refresh.
func (c *Client) DidChange(path, text string) {
uri := pathToURI(path)
ver := c.bumpDoc(uri, text)
c.notify("textDocument/didChange", map[string]any{
"textDocument": map[string]any{"uri": uri, "version": ver},
"contentChanges": []any{map[string]any{"text": text}},
})
}
// DidClose stops diagnostics for a document (e.g. when switching files).
func (c *Client) DidClose(path string) {
uri := pathToURI(path)
c.docMu.Lock()
delete(c.docs, uri)
c.docMu.Unlock()
c.notify("textDocument/didClose", map[string]any{
"textDocument": map[string]any{"uri": uri},
})
}
// Close shuts the subprocess down. Best-effort: it asks harper to exit, closes
// stdin, then kills and reaps the process asynchronously so Close never blocks
// and leaves no zombie behind.
func (c *Client) Close() error {
c.notify("exit", nil)
_ = c.stdin.Close()
err := c.cmd.Process.Kill()
go func() { _ = c.cmd.Wait() }() // reap the killed process
return err
}
// --- document bookkeeping -------------------------------------------------
func (c *Client) setDoc(uri string, version int, text string) {
c.docMu.Lock()
c.docs[uri] = docState{version: version, lines: strings.Split(text, "\n")}
c.docMu.Unlock()
}
func (c *Client) bumpDoc(uri, text string) int {
c.docMu.Lock()
defer c.docMu.Unlock()
d := c.docs[uri]
d.version++
if d.version < 1 {
d.version = 1
}
d.lines = strings.Split(text, "\n")
c.docs[uri] = d
return d.version
}
func (c *Client) docLines(uri string) ([]string, bool) {
c.docMu.Lock()
defer c.docMu.Unlock()
d, ok := c.docs[uri]
return d.lines, ok
}
// --- LSP wire -------------------------------------------------------------
func (c *Client) initialize() {
root := "file://" + osGetwd()
c.request("initialize", map[string]any{
"processId": os.Getpid(),
"rootUri": root,
"capabilities": map[string]any{
"workspace": map[string]any{"configuration": true},
"textDocument": map[string]any{"publishDiagnostics": map[string]any{}},
},
})
<-c.ready // block until harper answers initialize
c.notify("initialized", map[string]any{})
}
func (c *Client) request(method string, params any) int {
c.writeMu.Lock()
c.nextID++
id := c.nextID
c.writeMu.Unlock()
c.send(map[string]any{"jsonrpc": "2.0", "id": id, "method": method, "params": params})
return id
}
func (c *Client) notify(method string, params any) {
c.send(map[string]any{"jsonrpc": "2.0", "method": method, "params": params})
}
func (c *Client) respond(id json.RawMessage, result any) {
c.send(map[string]any{"jsonrpc": "2.0", "id": id, "result": result})
}
func (c *Client) send(v map[string]any) {
body, err := json.Marshal(v)
if err != nil {
return
}
c.writeMu.Lock()
defer c.writeMu.Unlock()
_ = writeFrame(c.stdin, body)
}
// readLoop parses harper's frames until the stream closes, answering the server
// requests that gate diagnostics and forwarding publishDiagnostics onward.
func (c *Client) readLoop(r *bufio.Reader) {
defer close(c.done)
initID := 1 // initialize is always the first request
for {
body, err := readFrame(r)
if err != nil {
return
}
var m struct {
ID json.RawMessage `json:"id"`
Method string `json:"method"`
Params json.RawMessage `json:"params"`
}
if json.Unmarshal(body, &m) != nil {
continue
}
switch {
case m.Method == "" && len(m.ID) > 0: // response to one of our requests
if string(m.ID) == itoa(initID) {
c.signalReady()
}
case len(m.ID) > 0: // server -> client request: must answer or diagnostics stall
c.answerRequest(m.ID, m.Method, m.Params)
case m.Method == "textDocument/publishDiagnostics":
c.handleDiagnostics(m.Params)
}
}
}
func (c *Client) signalReady() {
select {
case <-c.ready:
default:
close(c.ready)
}
}
// answerRequest replies to the server-initiated requests harper needs before it
// will emit diagnostics: workspace/configuration wants one config object per
// requested item (empty = harper defaults); everything else gets a null result.
func (c *Client) answerRequest(id json.RawMessage, method string, params json.RawMessage) {
if method == "workspace/configuration" {
var p struct {
Items []json.RawMessage `json:"items"`
}
_ = json.Unmarshal(params, &p)
result := make([]any, len(p.Items))
for i := range result {
result[i] = map[string]any{}
}
c.respond(id, result)
return
}
c.respond(id, nil)
}
func (c *Client) handleDiagnostics(params json.RawMessage) {
var p struct {
URI string `json:"uri"`
Diagnostics []struct {
Range struct {
Start struct{ Line, Character int } `json:"start"`
End struct{ Line, Character int } `json:"end"`
} `json:"range"`
Message string `json:"message"`
Code any `json:"code"`
} `json:"diagnostics"`
}
if json.Unmarshal(params, &p) != nil {
return
}
lines, ok := c.docLines(p.URI)
if !ok {
return // diagnostics for a document we no longer track
}
var batch []Diag
for _, d := range p.Diagnostics {
batch = append(batch, lspRangeToDiags(lines,
d.Range.Start.Line, d.Range.Start.Character,
d.Range.End.Line, d.Range.End.Character,
d.Message, codeString(d.Code))...)
}
c.publish(batch)
}
// publish delivers batch on the depth-1 channel, replacing any undrained batch so
// the reader always gets the newest diagnostics and the read loop never blocks.
func (c *Client) publish(batch []Diag) {
for {
select {
case c.diags <- batch:
return
default:
select {
case <-c.diags:
default:
}
}
}
}
|