Parsing Expressions and Programs

With tokens in hand, the next stretch of commits built a recursive-descent expression parser and then wrapped it in a program structure that could hold more than one statement.

Expressions, in the order operator precedence demands

The parser grew in the textbook order for precedence climbing:

1. Integer literals and parenthesized error handling (b3ea2aa).
2. Addition and subtraction (c0daf03).
3. Multiplication and parenthesized precedence (99d11f7) — multiplication had to bind tighter than the addition/subtraction level added just before it, and parentheses had to override both.

Each step landed with its own parser test, so by the time semantic evaluation existed, the precedence rules were already locked down by regression tests rather than by hope.

From a single expression to a program

6be02df — Implement program parsing and testing introduced the core model that the rest of the assembler still uses: a Program is a flat, growable array of Statement values (include/program.h). Two tests still in the suite trace directly back to this commit:

• program_blocks.c / parser_blocks.cmake — multiple statements parse into the same flat array.
• program_growth.c — the array actually grows past its initial capacity without corrupting existing entries.

Nested blocks are parser sugar, not a runtime concept

08cdd02 — Add support for nested blocks in parser added { } grouping with an explicit depth limit. Nested blocks never became a distinct concept in the Program model — they are flattened into the same statement array during parsing. This is a deliberate simplification: nothing downstream (layout, encoding, decoding) ever needs to know a block existed. It is worth calling out specifically because it is easy to assume, from the syntax alone, that blocks are scopes or basic blocks in a compiler sense. They are not; they are purely a source-level grouping convenience.

By the end of this phase, Kasm could parse a full program of expressions and statements — but it still couldn’t validate or encode anything. That came next, in 0.1.0.