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LibertyXDR: add support for default in unions

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Přemysl Eric Janouch 2025-05-07 19:42:46 +02:00
parent 9a26284a64
commit b69d3f8692
Signed by: p
GPG Key ID: A0420B94F92B9493
3 changed files with 30 additions and 7 deletions
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6
libertyxdr.adoc
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@ -93,10 +93,12 @@ and always-present field, which must be a tag *enum*:
case CAR: void; case CAR: void;
case LORRY: i8 axles; case LORRY: i8 axles;
case PLANE: i8 engines; case PLANE: i8 engines;
default: void;
}; };
All possible enumeration values must be named, and there is no *case* There is no *case* fall-through.
fall-through. Unless *default* is present, only the listed enumeration values are valid.
Any *default* must currently be empty.
Framing Framing
------- -------

2
tests/lxdrgen.lxdr
View File

@ -25,5 +25,7 @@ struct Struct {
union Onion switch (Enum tag) { union Onion switch (Enum tag) {
case NOTHING: case NOTHING:
void; void;
default:
void;
} o; } o;
}; };

29
tools/lxdrgen.awk
View File

@ -1,6 +1,6 @@
# lxdrgen.awk: an XDR-derived code generator for network protocols. # lxdrgen.awk: an XDR-derived code generator for network protocols.
# #
# Copyright (c) 2022 - 2023, Přemysl Eric Janouch <p@janouch.name> # Copyright (c) 2022 - 2025, Přemysl Eric Janouch <p@janouch.name>
# SPDX-License-Identifier: 0BSD # SPDX-License-Identifier: 0BSD
# #
# Usage: env LC_ALL=C awk -f lxdrgen.awk -f lxdrgen-{c,go,mjs}.awk \ # Usage: env LC_ALL=C awk -f lxdrgen.awk -f lxdrgen-{c,go,mjs}.awk \
@ -218,7 +218,7 @@ function defstruct( name, d, cg) {
} }
function defunion( name, tag, tagtype, tagvalue, cg, scg, d, a, i, function defunion( name, tag, tagtype, tagvalue, cg, scg, d, a, i,
unseen, exhaustive) { unseen, defaulted, exhaustive) {
delete cg[0] delete cg[0]
delete scg[0] delete scg[0]
delete d[0] delete d[0]
@ -249,9 +249,22 @@ function defunion( name, tag, tagtype, tagvalue, cg, scg, d, a, i,
if (!unseen[tagvalue]--) if (!unseen[tagvalue]--)
fatal("no such value or duplicate case: " tagtype "." tagvalue) fatal("no such value or duplicate case: " tagtype "." tagvalue)
codegen_struct_tag(tag, scg) codegen_struct_tag(tag, scg)
} else if (accept("default")) {
if (tagvalue)
codegen_union_struct(name, tagvalue, cg, scg)
expect(accept(":"))
if (defaulted)
fatal("duplicate default")
tagvalue = ""
defaulted = 1
} else if (tagvalue) { } else if (tagvalue) {
if (readfield(d)) if (readfield(d))
codegen_struct_field(d, scg) codegen_struct_field(d, scg)
} else if (defaulted) {
if (readfield(d))
fatal("default must not contain fields")
} else { } else {
fatal("union fields must fall under a case") fatal("union fields must fall under a case")
} }
@ -259,11 +272,17 @@ function defunion( name, tag, tagtype, tagvalue, cg, scg, d, a, i,
if (tagvalue) if (tagvalue)
codegen_union_struct(name, tagvalue, cg, scg) codegen_union_struct(name, tagvalue, cg, scg)
# Unseen cases are simply not recognized/allowed. # Unseen cases are only recognized/allowed when default is present.
exhaustive = 1 exhaustive = 1
for (i in unseen) for (i in unseen)
if (i && unseen[i]) if (i && unseen[i]) {
exhaustive = 0 if (defaulted) {
codegen_struct_tag(tag, scg)
codegen_union_struct(name, i, cg, scg)
} else {
exhaustive = 0
}
}
Types[name] = "union" Types[name] = "union"
codegen_union(name, cg, exhaustive) codegen_union(name, cg, exhaustive)