Merge pull request #2315 from GaijinEntertainment/string-lint

Add performance lint module, first_character/with_das_string builtins, optimize character_at

Author: borisbat

.github/workflows/build.yml

@@ -2,6 +2,7 @@ name: build
 
 on:
   push:
+    branches: [master]
   pull_request:
   workflow_dispatch:
   release:

CLAUDE.md

@@ -99,6 +99,7 @@ Task-specific instructions are split into skill files under `skills/`. You MUST
 | `skills/aot_testing.md` | Adding AOT test files, working with the `test_aot` binary, `Module::aotRequire()`, CMake AOT macros, **debugging AOT hash mismatches** |
 | `skills/visitor_gen_bind.md` | Adding or modifying `Visitor` virtual methods, `canVisit*` gates, running `gen_bind.das`, updating adapter bindings in `ast_gen.inc` |
 | `skills/daslang_live.md` | Working with `daslang-live.exe`, live-reload lifecycle, REST API, `[live_command]`, `[before_reload]`/`[after_reload]`, persistent store, `live/glfw_live`, `live/live_api` |
+| `skills/perf_lint.md` | Adding new performance lint rules to `daslib/perf_lint.das` |
 
 Multiple skill files may apply to a single task. For example, creating a new daslib module requires reading `skills/das_formatting.md`, `skills/daslib_modules.md`, and possibly `skills/documentation_rst.md`.
 
@@ -174,6 +175,7 @@ All code MUST use gen2 syntax (add `options gen2` at the top of every file). Key
 
 - `try/recover` — NOT `try/catch` (`recover` is the keyword)
 - `panic("message")`, `assert(condition)`, `verify(condition)` (stays in release)
+- **Postfix conditional:** `return expr if (cond)`, `break if (cond)`, `continue if (cond)` — early-exit guard on one line
 
 ### Generic function dispatch
 
@@ -196,6 +198,13 @@ All code MUST use gen2 syntax (add `options gen2` at the top of every file). Key
 - When the iterator is named `each`, the call can be omitted: `for (v in each(x))` is identical to `for (v in x)`
 - Other iterator names (e.g. `filter`, `map`) cannot be omitted
 
+### String access functions
+
+- **`peek_data(str) $(arr) { ... }`** — safe O(1) per-element read access to string as `array<uint8> const#`. One `strlen` call total. Preferred over `character_at` for iteration.
+- **`modify_data(str) $(var arr) { ... }`** — returns a modified copy; allocates new string, opens as mutable `array<uint8>`. Use for character-level transformations.
+- **`character_at(s, i)`** — O(n) per call (`strlen` + bounds check). Fine for isolated checks, but use `peek_data` in loops or hot paths.
+- Pointer-based string access (`reinterpret<uint8?>`) is for core library implementations only — user code should use `peek_data`/`modify_data` for safety.
+
 ### Common gotchas
 
 - Lambda params can shadow function params — use distinct names

daslib/aot_cpp.das

@@ -1655,7 +1655,7 @@ class public CppAot : AstVisitor {
         }
     }
     def isOpPolicy1(that : smart_ptr<ExprOp1>) {
-        if (is_alpha(character_at(string(that.op), 0))) {
+        if (is_alpha(first_character(that.op))) {
             return true;
         }
         return that.subexpr._type.isPolicyType;
@@ -1688,8 +1688,7 @@ class public CppAot : AstVisitor {
             write(*ss, ",*__context__,nullptr)");
         } else {
             if (that.op == "+++" || that.op == "---") {
-                *ss |> write_char(character_at(string(that.op), 0))
-                *ss |> write_char(character_at(string(that.op), 1));
+                write(*ss, slice(string(that.op), 0, 2));
             }
             if (!noBracket(that) && !that.subexpr.printFlags.bottomLevel) {
                 write(*ss, ")");
@@ -1703,7 +1702,7 @@ class public CppAot : AstVisitor {
                 that.right._type.baseType == Type.tBool && that.right._type.isSimpleType);
     }
     def isOpPolicy2(that : smart_ptr<ExprOp2>) {
-        if (is_alpha(character_at(string(that.op), 0))) return true;
+        if (is_alpha(first_character(that.op))) return true;
         if (that.op == "/" || that.op == "%") return true;
         if (that.op == "<<<" || that.op == ">>>" || that.op == "<<<=" || that.op == ">>>=") return true;
         if (that.op == "<<" || that.op == ">>" || that.op == "<<=" || that.op == ">>=") return true;
@@ -2537,10 +2536,10 @@ class public CppAot : AstVisitor {
             write(*ss, "das_swizzle_ref<{type_str},{value_str},{int(expr.fields[0])}>::swizzle(");
         } else {
             if (length(expr.fields) == 1) {
-                let mask = "xyzw";
+                let mask = fixed_array('x', 'y', 'z', 'w');
                 let is64bit = expr._type.baseType == Type.tInt64 || expr._type.baseType == Type.tUInt64;
                 write(*ss, "v_extract_")
-                *ss |> write_char(character_at(mask, int(expr.fields[0])));
+                *ss |> write_char(mask[int(expr.fields[0])]);
                 if (expr._type.baseType != Type.tFloat) {
                     write(*ss, is64bit ? "i64" : "i");
                 }