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* docs: add local full-text search and a contributor README Add @easyops-cn/docusaurus-search-local to the Docusaurus site so the docs get an offline search bar (index built at build time, no external service). English and zh-CN pages are both indexed, and matched terms are highlighted on the target page. Add docs/README.md describing the Docusaurus setup, local dev/build commands, search behavior, directory layout, and gotchas; exclude it from the published site alongside CLAUDE.md. Point the root README's docs/ entry at it. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01TSzcESzU9947zkGzQ6SMmE * docs: remove dead framework leftovers, fix index generation, complete the nav Delete the VitePress (.vitepress/) and Jekyll (_layouts/, css/) leftovers, the one-shot migration scripts (fix_md_header.py, fix_seealso.py), and the stale keywords.json snapshot; prune the matching .gitignore entries and docusaurus exclude patterns. Rewrite gen_index.py for Docusaurus: it emitted dead .html links and legacy 'layout: doc' frontmatter, choked on non-markdown entries, and dropped nested categories — regenerating an index would have broken it. It now emits the extension-less links the site actually uses, links nested category indexes (restoring apply/* on the zh-CN index), and refuses to run on the docs root. Fix update_index.sh's copy-paste titles (zh-CN efun/build were titled 'APPLY'), stop it clobbering the hand-written lpc/index.md, and cover cli/. Regenerated indexes pick up the missing driver/ffi-plan entry. add_missing_efuns.py now takes the keywords.json path as an argument instead of requiring a stale copy. Move CNAME and the Google site-verification file into static/ so they actually reach the published build output. Complete the sidebar: link the CLI category to cli/index and add the missing portbind/symbol/generate_keywords pages, and expose the previously orphaned stdlib section under Reference. Promote onBrokenLinks to 'throw' now the build is warning-free, and drop the empty Demo section from the landing page. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01TSzcESzU9947zkGzQ6SMmE * docs: strip legacy 'layout: doc' frontmatter from all pages Mechanical sweep removing the Jekyll-era 'layout: doc' line from every doc page's frontmatter (Docusaurus ignores it), and the matching line from the templates in docs/CLAUDE.md so new pages don't reintroduce it. No content changes. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01TSzcESzU9947zkGzQ6SMmE --------- Co-authored-by: Claude <noreply@anthropic.com>
65 lines
1.6 KiB
Markdown
65 lines
1.6 KiB
Markdown
---
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title: preprocessor / conditionals
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---
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# Conditional compilation
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`#if`, `#ifdef`, `#ifndef`, `#elif`, `#else` and `#endif` select which
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regions of a file the compiler sees.
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```c
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#ifdef __PACKAGE_SOCKETS__
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int open_port() { return socket_create(STREAM, "cb"); }
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#else
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int open_port() { return -1; }
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#endif
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```
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## #ifdef / #ifndef
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Test only whether a macro is defined (user `#define`s and driver
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predefines both count):
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```c
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#ifndef MUDLIB_H
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#define MUDLIB_H
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...
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#endif // classic include guard
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```
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## #if expressions
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`#if` and `#elif` evaluate an integer constant expression. Macros in
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the expression are expanded first; the expression is then evaluated
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**over tokens with full C operator precedence** — parentheses, unary
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`! ~ -`, arithmetic `* / % + -`, shifts, comparisons, bitwise
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`& ^ |`, and logical `&& ||`:
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```c
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#define X 1+1
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#if X*2 == 3 // expands to 1+1*2 -- true, as in C
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#endif
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```
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Two extra operators are available:
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* `defined(NAME)` (or `defined NAME`) — 1 if `NAME` is a defined
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macro.
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* `efun_defined(name)` — 1 if the driver was built with the named
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efun.
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```c
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#if defined(__PACKAGE_CRYPTO__) && efun_defined(hash)
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string h = hash("sha256", data);
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#endif
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```
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An undefined identifier appearing in an `#if` expression evaluates to
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`0`, as in C. A missing expression is a compile error.
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## Nesting and skipped regions
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Conditionals nest arbitrarily. Inside a false branch the compiler
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still tracks `#if`/`#endif` nesting (so a skipped region may contain
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its own conditionals), but nothing else in the region is evaluated —
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including other directives. An unmatched `#elif`/`#else`/`#endif` is
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a compile error.
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