Refactor pasers to use AST when possible

Author: AJenbo

docs/ARCHITECTURE.md

@@ -19,7 +19,7 @@ src/
 ├── lib.rs                  # Backend struct, state, constructors
 ├── main.rs                 # Entry point (stdin/stdout LSP transport)
 ├── server.rs               # LSP protocol handlers (initialize, didOpen, completion, …)
-├── types.rs                # Data structures (ClassInfo, MethodInfo, PropertyInfo, …)
+├── types.rs                # Data structures (ClassInfo, MethodInfo, SubjectExpr, ResolvedCallableTarget, …)
 ├── composer.rs             # composer.json / PSR-4 autoload parsing
 ├── stubs.rs                # Embedded phpstorm-stubs (build-time generated index)
 ├── resolution.rs           # Multi-phase class/function lookup and name resolution
@@ -48,8 +48,8 @@ src/
 │   ├── mod.rs              # Submodule declarations
 │   ├── handler.rs          # Top-level completion request orchestration
 │   ├── target.rs           # Extract what the user is completing (subject + access kind)
-│   ├── resolver.rs         # Resolve subject → ClassInfo (type resolution engine)
-│   ├── text_resolution.rs  # Text-based type resolution (assignment scanning, call chains)
+│   ├── resolver.rs         # Resolve subject → ClassInfo (type resolution engine), shared resolve_callable_target
+│   ├── source_helpers.rs   # Source-text scanning helpers (closure/callable return types, new-expression parsing, array access)
 │   ├── builder.rs          # Build LSP CompletionItems from resolved ClassInfo
 │   ├── class_completion.rs # Class name, constant, and function completions
 │   ├── variable_completion.rs  # Variable name completions and scope collection
@@ -129,21 +129,19 @@ A value of `0` means "not available" (stubs parsed before offsets were stored, s
 
 ### Tier 3: Text-Based Fallback (deprecated)
 
-The original line-by-line text scanners (`extract_word_at_position`, `find_member_position_in_range` text search, `line_defines_variable`, `find_definition_position`, `find_function_position`) are retained as fallbacks for:
+The remaining line-by-line text scanners (`extract_word_at_position`, `find_member_position_in_range` text search, `find_definition_position`, `find_function_position`) are retained as fallbacks for:
 
-- Stubs and synthetic members where `name_offset == 0`
+- Stubs and synthetic members where `name_offset == 0` or `keyword_offset == 0`
 - Files where the parser panicked (malformed PHP) and no symbol map exists
-- The go-to-implementation subsystem (not yet migrated to the symbol map)
 
-These functions are marked `#[deprecated]` with phase notes. They will be removed once the AST-based paths have been stable for a release cycle.
+These functions are marked `#[deprecated]` with phase notes. They will be removed once stubs and synthetic members store valid byte offsets during parsing.
 
 ### Variable Definition Resolution
 
-Variable go-to-definition (`$var` → jump to definition) uses three layers:
+Variable go-to-definition (`$var` → jump to definition) uses two layers:
 
 1. **Symbol map** (`var_defs`): the primary path. Finds the most recent `VarDefSite` before the cursor within the enclosing scope. When the cursor is physically on a definition token (parameter, foreach binding, catch variable), it returns `None` so the caller can fall through to type-hint resolution.
-2. **AST-based search** (`resolve_variable_definition_ast`): parses the file and walks the enclosing scope to find the definition site. Handles destructuring (`[$a, $b] = ...`, `list($a, $b) = ...`) and nested scopes correctly. Used as a fallback when the symbol map doesn't have a match.
-3. **Text-based search** (`resolve_variable_definition_text`): the original heuristic line scanner. Only activated when the AST parse fails.
+2. **AST-based search** (`resolve_variable_definition_ast`): parses the file and walks the enclosing scope to find the definition site. Handles destructuring (`[$a, $b] = ...`, `list($a, $b) = ...`) and nested scopes correctly. Used as a fallback when the symbol map doesn't have a match. Returns `None` when the AST parse fails.
 
 ## Signature Help Architecture
 

docs/CHANGELOG.md

@@ -824,39 +824,7 @@ See `ClosureBindDynamicReturnTypeExtension` and
 
 ---
 
-### 27. Remove deprecated text-search fallbacks
-**Impact: Low · Effort: Medium**
-
-The go-to-definition subsystem now uses the precomputed `SymbolMap` as
-its primary path and stored byte offsets (`name_offset`, `keyword_offset`)
-for cross-file jumps. The original line-by-line text scanners are marked
-`#[deprecated]` and retained only as fallbacks for:
-
-- Stubs and synthetic members where `name_offset == 0`
-- Files where the parser panicked and no symbol map exists
-- The go-to-implementation subsystem (not yet migrated)
-
-Once the AST-based paths have been stable for a release cycle, these
-deprecated functions can be removed:
-
-| Function | File | Replacement |
-|---|---|---|
-| `find_definition_position` | `definition/resolve.rs` | `ClassInfo::keyword_offset` + `offset_to_position` |
-| `find_function_position` | `definition/resolve.rs` | `FunctionInfo::name_offset` + `offset_to_position` |
-| `find_define_position` | `definition/resolve.rs` | Store `define()` offset during parsing |
-| `extract_word_at_position` | `definition/resolve.rs` | `SymbolMap::lookup` |
-| `resolve_variable_definition_text` | `definition/variable.rs` | `SymbolMap::find_var_definition` + AST walk |
-| `line_defines_variable` | `definition/variable.rs` | (only used by `resolve_variable_definition_text`) |
-| `find_member_position_in_range` text path | `definition/member.rs` | `name_offset` + `offset_to_position` |
-
-The go-to-implementation subsystem (`resolve_implementation` in
-`definition/implementation.rs`) still uses `extract_word_at_position`
-for cursor context detection. Migrating it to use `SymbolMap::lookup`
-would let that deprecated function be removed entirely.
-
----
-
-### 28. Non-array functions with dynamic return types
+### 27. Non-array functions with dynamic return types
 **Impact: Low · Effort: High**
 
 PHPStan also provides dynamic return type extensions for many non-array
@@ -887,7 +855,7 @@ return types (less impactful for class-based completion).
 
 ---
 
-### 29. Language construct signature help and hover
+### 28. Language construct signature help and hover
 **Impact: Low · Effort: Low**
 
 PHP language constructs that use parentheses (`unset()`, `isset()`, `empty()`,
@@ -904,22 +872,22 @@ need a similar hardcoded lookup.
 
 ---
 
-### 30. Diagnostics
+### 29. Diagnostics
 **Impact: Low (large scope) · Effort: Very High**
 
 No error reporting (undefined methods, type mismatches, etc.).
 
 ---
 
-### 31. Code Actions
+### 30. Code Actions
 **Impact: Low · Effort: Very High**
 
 No quick fixes or refactoring suggestions. No `codeActionProvider` in
 `ServerCapabilities`, no `textDocument/codeAction` handler, and no
 `WorkspaceEdit` generation infrastructure beyond trivial `TextEdit`s for
 use-statement insertion.
 
-#### 31a. Extract Function refactoring
+#### 30a. Extract Function refactoring
 
 Select a range of statements inside a method/function and extract them into a
 new function. The LSP would need to: