Basic implementation of language server document highlight.

If the cursor is on a symbol, this will highlight all the symbols
in the buffer with the same name (it does _not_ take naming
scopes into account yet).

Signed-off-by: Henner Zeller <[email protected]>

common/lsp/lsp-protocol.yaml

@@ -49,6 +49,11 @@ TextDocumentContentChangeEvent:
   range?: Range     # Range optional; if no range given, full document replace
   text: string
 
+# For hover or highlight
+TextDocumentPositionParams:
+  textDocument: TextDocumentIdentifier
+  position: Position
+
 # -- Text document notifiations. These allow us to keep track of the content.
 DidOpenTextDocumentParams:      # textDocument/didOpen
   textDocument: TextDocumentItem
@@ -108,3 +113,11 @@ DocumentSymbol:
   # children: DocumentSymbol[]. Since we can't to that recursively in jcxxgen,
   # these are directly emitted as json
   children?: object = nullptr
+
+# -- textDocument/documentHighlight
+DocumentHighlightParams:
+  <: TextDocumentPositionParams
+
+DocumentHighlight:         # response documentHighlight is [] of this.
+  range: Range
+  # there is also a highlight kind to distinguish read/write

verilog/tools/ls/BUILD

@@ -36,6 +36,7 @@ cc_library(
         "//common/text:text_structure",
         "//verilog/analysis:verilog_analyzer",
         "//verilog/analysis:verilog_linter",
+        "//verilog/parser:verilog_token_enum",
         "@jsonhpp",
     ],
 )

verilog/tools/ls/README.md

@@ -17,7 +17,8 @@ progress
   - [x] Provide code actions for autofixes provided by lint rules
   - [x] Generate file symbol outline ('navigation tree')
   - [ ] Provide formatting.
-  - [ ] Highlight all the symbols that are the same as current under cursor.
+  - [x] Highlight all the symbols that are the same as current under cursor.
+    - [ ] Take scope and type into account to only highlight _same_ symbols.
   - [ ] Find definition of symbol even if in another file.
   - [ ] Rename refactor a symbol
 

verilog/tools/ls/verible-lsp-adapter.cc

@@ -21,6 +21,7 @@
 #include "nlohmann/json.hpp"
 #include "verilog/analysis/verilog_analyzer.h"
 #include "verilog/analysis/verilog_linter.h"
+#include "verilog/parser/verilog_token_enum.h"
 #include "verilog/tools/ls/document-symbol-filler.h"
 #include "verilog/tools/ls/lsp-parse-buffer.h"
 
@@ -172,4 +173,35 @@ nlohmann::json CreateDocumentSymbolOutline(
   return toplevel.children;
 }
 
+std::vector<verible::lsp::DocumentHighlight> CreateHighlightRanges(
+    const BufferTracker *tracker,
+    const verible::lsp::DocumentHighlightParams &p) {
+  std::vector<verible::lsp::DocumentHighlight> result;
+  if (!tracker) return result;
+  const ParsedBuffer *const current = tracker->current();
+  if (!current) return result;
+  const verible::LineColumn cursor{p.position.line, p.position.character};
+  const verible::TextStructureView &text = current->parser().Data();
+  const verible::TokenInfo cursor_token = text.FindTokenAt(cursor);
+
+  if (cursor_token.token_enum() == SymbolIdentifier) {
+    // Find all the symbols with the same name in the buffer.
+    // Note, this is very simplistic as it does _not_ take scopes into account.
+    // For that, we'd need the symbol table, but that implementation is not
+    // complete yet.
+    for (const verible::TokenInfo &tok : text.TokenStream()) {
+      if (tok.token_enum() != cursor_token.token_enum()) continue;
+      if (tok.text() != cursor_token.text()) continue;
+      const verible::LineColumnRange range = text.GetRangeForToken(tok);
+      result.push_back(verible::lsp::DocumentHighlight{
+          .range = {
+              .start = {.line = range.start.line,
+                        .character = range.start.column},
+              .end = {.line = range.end.line, .character = range.end.column},
+          }});
+    }
+  }
+  return result;
+}
+
 }  // namespace verilog

verilog/tools/ls/verible-lsp-adapter.h

@@ -42,5 +42,13 @@ std::vector<verible::lsp::CodeAction> GenerateLinterCodeActions(
 nlohmann::json CreateDocumentSymbolOutline(
     const BufferTracker *tracker, const verible::lsp::DocumentSymbolParams &p,
     bool kate_compatible_tags = true);
+
+// Give a position in a document, return ranges in the buffer that should
+// be hi-lit.
+// Current implementation: if cursor is over a symbol, highlight all symbols
+// with the same name (NB: Does _not_ take scoping into account yet).
+std::vector<verible::lsp::DocumentHighlight> CreateHighlightRanges(
+    const BufferTracker *tracker,
+    const verible::lsp::DocumentHighlightParams &p);
 }  // namespace verilog
 #endif  // VERILOG_TOOLS_LS_VERIBLE_LSP_ADAPTER_H

verilog/tools/ls/verilog_ls.cc

@@ -61,8 +61,9 @@ static InitializeResult InitializeServer(const nlohmann::json &params) {
               {"change", 2},        // Incremental updates
           },
       },
-      {"codeActionProvider", true},      // Autofixes for lint errors
-      {"documentSymbolProvider", true},  // Outline of file
+      {"codeActionProvider", true},         // Autofixes for lint errors
+      {"documentSymbolProvider", true},     // Symbol-outline of file
+      {"documentHighlightProvider", true},  // Highlight same symbol
   };
 
   return result;
@@ -133,22 +134,27 @@ int main(int argc, char *argv[]) {
   // Exchange of capabilities.
   dispatcher.AddRequestHandler("initialize", InitializeServer);
 
-  // Provide autofixes
-  dispatcher.AddRequestHandler(
+  dispatcher.AddRequestHandler(  // Provide autofixes
       "textDocument/codeAction",
       [&parsed_buffers](const verible::lsp::CodeActionParams &p) {
         return verilog::GenerateLinterCodeActions(
             parsed_buffers.FindBufferTrackerOrNull(p.textDocument.uri), p);
       });
 
-  // Provide outline
-  dispatcher.AddRequestHandler(
+  dispatcher.AddRequestHandler(  // Provide document outline/index
       "textDocument/documentSymbol",
       [&parsed_buffers](const verible::lsp::DocumentSymbolParams &p) {
         return verilog::CreateDocumentSymbolOutline(
             parsed_buffers.FindBufferTrackerOrNull(p.textDocument.uri), p);
       });
 
+  dispatcher.AddRequestHandler(  // Highlight related symbols under cursor
+      "textDocument/documentHighlight",
+      [&parsed_buffers](const verible::lsp::DocumentHighlightParams &p) {
+        return verilog::CreateHighlightRanges(
+            parsed_buffers.FindBufferTrackerOrNull(p.textDocument.uri), p);
+      });
+
   // The client sends a request to shut down. Use that to exit our loop.
   bool shutdown_requested = false;
   dispatcher.AddRequestHandler("shutdown",