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Compiler Frontend

The Aipo frontend ingests raw UTF-8 source text and produces a validated semantic representation.

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Pipeline Stages

1. aipo-source

• Encapsulates source files and in-memory buffers.
• Delivers UTF-8 boundary-safe line and column offsets (is_char_boundary), ensuring strict MSRV compatibility (Rust 1.85+).

2. aipo-lexer

• Converts the UTF-8 character stream into a contiguous sequence of tokens.
• Zero-copy optimizations for keywords and operators via direct pattern matching over &str.
• Canonical rejection of malformed floating-point literals (such as 1.e5 or 1._5), generating the diagnostic AIPO_LEX_INVALID_NUMBER.

3. aipo-syntax & aipo-ast

• Recursive-descent parser with resilient panic-mode synchronization recovery (synchronize).
• Preserves async annotations in interface method contracts.
• Parser desugaring of chained comparisons (e.g., val >= 0 and <= 100).
• First-class support for inline ternary conditionals (if c then a else b).

4. aipo-hir

• Lowers the AST into High-Level Intermediate Representation (HIR).
• Unifies source spans across lifecycle hooks (init and invariant).
• Resolves local lexical bindings and top-level module scope identifiers.

5. aipo-sema

• Semantic validator enforcing strict structural typing and contract safety:
  • Enforces interface contracts via automatic structural subtyping (validating required methods, parameter arities, self vs var self receiver mutability, and type compatibility).
  • Statically disallows reassigning immutable struct fields (AIPO_SEM_IMMUTABLE_FIELD_REASSIGN).
  • Emits concurrency diagnostics (AIPO_SEM_AWAIT_IN_SUBEXPRESSION, AIPO_SEM_FORGOTTEN_TASK, AIPO_SEM_NESTED_AWAIT_DO).