From 8cf6029f1acac5b49297188be5c0f390f6ae193d Mon Sep 17 00:00:00 2001
From: Alexandros Naskos <alex_naskos@hotmail.com>
Date: Wed, 31 Mar 2021 02:25:49 +0300
Subject: [PATCH] Before documentPositionContext returns .empty, check if an
 identifier   immediately follows the cursor and return .var_access if it does
   instead. This allows hover and go to definition to work when the cursor is 
  immediately before an identifier.

---
 src/analysis.zig | 31 +++++++++++++++++++++++++++++--
 src/main.zig     | 14 ++++++--------
 src/offsets.zig  | 12 ++++++++++--
 3 files changed, 45 insertions(+), 12 deletions(-)

diff --git a/src/analysis.zig b/src/analysis.zig
index 16b3f5b..04dafda 100644
--- a/src/analysis.zig
+++ b/src/analysis.zig
@@ -1549,7 +1549,11 @@ fn tokenRangeAppend(prev: SourceRange, token: std.zig.Token) SourceRange {
 
 const DocumentPosition = @import("offsets.zig").DocumentPosition;
 
-pub fn documentPositionContext(arena: *std.heap.ArenaAllocator, document: types.TextDocument, doc_position: DocumentPosition) !PositionContext {
+pub fn documentPositionContext(
+    arena: *std.heap.ArenaAllocator,
+    document: types.TextDocument,
+    doc_position: DocumentPosition,
+) !PositionContext {
     const line = doc_position.line;
     var tokenizer = std.zig.Tokenizer.init(line[0..doc_position.line_index]);
     var stack = try std.ArrayList(StackState).initCapacity(&arena.allocator, 8);
@@ -1639,7 +1643,30 @@ pub fn documentPositionContext(arena: *std.heap.ArenaAllocator, document: types.
     }
 
     return block: {
-        if (stack.popOrNull()) |state| break :block state.ctx;
+        if (stack.popOrNull()) |state| {
+            switch (state.ctx) {
+                .empty => {},
+                .label => |filled| {
+                    // We need to check this because the state could be a filled
+                    // label if only a space follows it
+                    const last_char = line[doc_position.line_index - 1];
+                    if (!filled or last_char != ' ') {
+                        break :block state.ctx;
+                    }
+                },
+                else => break :block state.ctx,
+            }
+        }
+        if (doc_position.line_index < line.len) {
+            switch (line[doc_position.line_index]) {
+                'a'...'z', 'A'...'Z', '_', '@' => {},
+                else => break :block .empty,
+            }
+            tokenizer = std.zig.Tokenizer.init(line[doc_position.line_index..]);
+            const tok = tokenizer.next();
+            if (tok.tag == .identifier)
+                break :block PositionContext{ .var_access = tok.loc };
+        }
         break :block .empty;
     };
 }
diff --git a/src/main.zig b/src/main.zig
index 14d6315..19b306e 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -357,8 +357,6 @@ fn nodeToCompletion(
     const node_tags = tree.nodes.items(.tag);
     const datas = tree.nodes.items(.data);
     const token_tags = tree.tokens.items(.tag);
-    if (tree.errors.len > 0)
-        return;
 
     const doc_kind: types.MarkupContent.Kind = if (client_capabilities.completion_doc_supports_md)
         .Markdown
@@ -1681,17 +1679,17 @@ fn processJsonRpc(arena: *std.heap.ArenaAllocator, parser: *std.json.Parser, jso
     logger.debug("Method without return value not implemented: {s}", .{method});
 }
 
-
 fn launchWizard() !void {
     const dest =
-        (try known_folders.getPath(allocator, .local_configuration))
-            orelse (try known_folders.getPath(allocator, .executable_dir))
-                orelse return error.NoConfigPathFound;
+        (try known_folders.getPath(allocator, .local_configuration)) orelse (try known_folders.getPath(allocator, .executable_dir)) orelse return error.NoConfigPathFound;
     defer allocator.free(dest);
     try setup.wizard(allocator, dest);
 }
 
-const stack_frames = switch (std.builtin.mode) { .Debug => 10, else => 0 };
+const stack_frames = switch (std.builtin.mode) {
+    .Debug => 10,
+    else => 0,
+};
 var gpa_state = std.heap.GeneralPurposeAllocator(.{ .stack_trace_frames = stack_frames }){};
 
 pub fn main() anyerror!void {
@@ -1711,7 +1709,7 @@ pub fn main() anyerror!void {
             std.debug.print("Enabled debug logging\n", .{});
         } else if (std.mem.eql(u8, arg, "config")) {
             try launchWizard();
-            args_it.deinit();            
+            args_it.deinit();
             return;
         } else {
             std.debug.print("Unrecognized argument {s}\n", .{arg});
diff --git a/src/offsets.zig b/src/offsets.zig
index 12c6471..534e6f7 100644
--- a/src/offsets.zig
+++ b/src/offsets.zig
@@ -30,7 +30,11 @@ pub fn documentPosition(doc: types.TextDocument, position: types.Position, encod
         if (index < 0 or index > @intCast(i64, doc.text.len)) {
             return error.InvalidParams;
         }
-        return DocumentPosition{ .line = line, .absolute_index = @intCast(usize, index), .line_index = @intCast(usize, position.character) };
+        return DocumentPosition{
+            .line = line,
+            .absolute_index = @intCast(usize, index),
+            .line_index = @intCast(usize, position.character),
+        };
     } else {
         const utf8 = doc.text[line_start_idx..];
         var utf8_idx: usize = 0;
@@ -50,7 +54,11 @@ pub fn documentPosition(doc: types.TextDocument, position: types.Position, encod
             }
             utf8_idx = next_utf8_idx;
         }
-        return DocumentPosition{ .line = line, .absolute_index = line_start_idx + utf8_idx, .line_index = utf8_idx };
+        return DocumentPosition{
+            .line = line,
+            .absolute_index = line_start_idx + utf8_idx,
+            .line_index = utf8_idx,
+        };
     }
 }