Files
c3c/resources/examples/contextfree/boolerr.c3

99 lines
2.5 KiB
C

module test;
import libc;
import std::io;
import std::collections::maybe;
def MaybeString = Maybe(<String>);
def MaybeHead = Maybe(<Head>);
def new_head_val = maybe::value(<Head>);
def new_string_val = maybe::value(<String>);
fault TitleResult
{
TITLE_MISSING
}
fault ReadError
{
BAD_READ,
}
struct Doc { MaybeHead head; }
struct Head { MaybeString title; }
struct Summary
{
MaybeString title;
bool ok;
}
fn void! Summary.print(Summary *s, OutStream* out)
{
io::fprintf(out, "Summary({ .title = %s, .ok = %s})", s.title.get() ?? "missing", s.ok)!;
}
fn Doc! read_doc(String url)
{
if (url.contains("fail")) return ReadError.BAD_READ?;
if (url.contains("head-missing")) return { };
if (url.contains("title-missing")) return { .head = new_head_val({}) };
if (url.contains("title-empty")) return { .head = new_head_val({ .title = new_string_val("")}) };
return { .head = new_head_val({ .title = new_string_val(string::new_format("Title of %s", url)) }) };
}
fn Summary build_summary(Doc doc)
{
return Summary {
.title = new_string_val(doc.head.get().title.get()) ?? MaybeString {},
.ok = true,
};
}
fn Summary read_and_build_summary(String url)
{
return build_summary(read_doc(url)) ?? Summary {};
}
fn bool! is_title_non_empty(Doc doc)
{
String! title = doc.head.get().title.get();
if (catch title) return TitleResult.TITLE_MISSING?;
return title.len > 0;
}
fn bool! read_whether_title_non_empty(String url)
{
return is_title_non_empty(read_doc(url));
}
fn String bool_to_string(bool b)
{
return b ? "true" : "false";
}
fn void main()
{
const String[] URLS = { "good", "title-empty", "title-missing", "head-missing", "fail" };
DynamicArenaAllocator dynamic_arena;
dynamic_arena.init(1024, mem::heap());
OutStream* out = io::stdout();
foreach (String url : URLS)
{
mem::@scoped(&dynamic_arena)
{
io::printf(`Checking "https://%s/":` "\n", url);
Summary summary = read_and_build_summary(url);
io::fprintf(out, " Summary: ")!!;
summary.print(out)!!;
io::fprintn(out, "")!!;
io::fprintf(out, " Title: %s\n", summary.title.get() ?? "")!!;
bool! has_title = read_whether_title_non_empty(url);
// This looks a bit less than elegant, but as you see it's mostly due to having to
// use printf here.
io::fprintf(out, " Has title: %s vs %s\n", bool_to_string(has_title) ?? (@catch(has_title)).nameof, has_title ?? false)!!;
};
dynamic_arena.reset();
}
dynamic_arena.free();
}