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# xC-gen-proto-js.awk: Javascript backend for xC-gen-proto.awk.
#
# Copyright (c) 2022, Přemysl Eric Janouch <p@janouch.name>
# SPDX-License-Identifier: 0BSD
#
# This backend is currently for decoding the binary format only.
# (JSON is way too expensive to process and transfer.)
#
# Import the resulting script as a Javascript module.
function define_internal(name) {
Types[name] = "internal"
}
function define_sint(size, shortname) {
shortname = "i" size
define_internal(shortname)
CodegenDeserialize[shortname] = "\t%s = r." shortname "()\n"
print ""
print "\t" shortname "() {"
if (size == "64") {
# XXX: 2^53 - 1 must be enough for anyone. BigInts are a PITA.
print "\t\tconst " shortname \
" = Number(this.getBigInt" size "(this.offset))"
} else {
print "\t\tconst " shortname " = this.getInt" size "(this.offset)"
}
print "\t\tthis.offset += " (size / 8)
print "\t\treturn " shortname
print "\t}"
}
function define_uint(size, shortname) {
shortname = "u" size
define_internal(shortname)
CodegenDeserialize[shortname] = "\t%s = r." shortname "()\n"
print ""
print "\t" shortname "() {"
if (size == "64") {
# XXX: 2^53 - 1 must be enough for anyone. BigInts are a PITA.
print "\t\tconst " shortname \
" = Number(this.getBigUint" size "(this.offset))"
} else {
print "\t\tconst " shortname " = this.getUint" size "(this.offset)"
}
print "\t\tthis.offset += " (size / 8)
print "\t\treturn " shortname
print "\t}"
}
function codegen_begin() {
print "export class Reader extends DataView {"
print "\tconstructor() {"
print "\t\tsuper(...arguments)"
print "\t\tthis.offset = 0"
print "\t\tthis.decoder = new TextDecoder('utf-8', {fatal: true})"
print "\t}"
print ""
print "\tget empty() {"
print "\t\treturn this.byteLength <= this.offset"
print "\t}"
print ""
print "\trequire(len) {"
print "\t\tif (this.byteLength - this.offset < len)"
print "\t\t\tthrow `Premature end of data`"
print "\t\treturn this.byteOffset + this.offset"
print "\t}"
define_internal("string")
CodegenDeserialize["string"] = "\t%s = r.string()\n"
print ""
print "\tstring() {"
print "\t\tconst len = this.getUint32(this.offset)"
print "\t\tthis.offset += 4"
print "\t\tconst array = new Uint8Array("
print "\t\t\tthis.buffer, this.require(len), len)"
print "\t\tthis.offset += len"
print "\t\treturn this.decoder.decode(array)"
print "\t}"
define_internal("bool")
CodegenDeserialize["bool"] = "\t%s = r.bool()\n"
print ""
print "\tbool() {"
print "\t\tconst u8 = this.getUint8(this.offset)"
print "\t\tthis.offset += 1"
print "\t\treturn u8 != 0"
print "\t}"
define_sint("8")
define_sint("16")
define_sint("32")
define_sint("64")
define_uint("8")
define_uint("16")
define_uint("32")
define_uint("64")
print "}"
}
function codegen_constant(name, value) {
print ""
print "export const " decapitalize(snaketocamel(name)) " = " value
}
function codegen_enum_value(name, subname, value, cg) {
append(cg, "fields", "\t" snaketocamel(subname) ": " value ",\n")
}
function codegen_enum(name, cg) {
print ""
print "export const " name " = Object.freeze({"
print cg["fields"] "})"
CodegenDeserialize[name] = "\t%s = r.i8()\n"
for (i in cg)
delete cg[i]
}
function codegen_struct_field(d, cg, camel, f, deserialize) {
camel = decapitalize(snaketocamel(d["name"]))
f = "s." camel
append(cg, "fields", "\t" camel "\n")
deserialize = CodegenDeserialize[d["type"]]
if (!d["isarray"]) {
append(cg, "deserialize", sprintf(deserialize, f))
return
}
append(cg, "deserialize",
"\t{\n" \
indent(sprintf(CodegenDeserialize["u32"], "const len")))
if (d["type"] == "u8") {
append(cg, "deserialize",
"\t\t" f " = new Uint8Array(\n" \
"\t\t\tr.buffer, r.require(len), len)\n" \
"\t\tr.offset += len\n" \
"\t}\n")
return
}
if (d["type"] == "i8") {
append(cg, "deserialize",
"\t\t" f " = new Int8Array(\n" \
"\t\t\tr.buffer, r.require(len), len)\n" \
"\t\tr.offset += len\n" \
"\t}\n")
return
}
append(cg, "deserialize",
"\t\t" f " = new Array(len)\n" \
"\t}\n" \
"\tfor (let i = 0; i < " f ".length; i++)\n" \
indent(sprintf(deserialize, f "[i]")))
}
function codegen_struct_tag(d, cg) {
append(cg, "fields", "\t" decapitalize(snaketocamel(d["name"])) "\n")
# Do not deserialize here, that is already done by the containing union.
}
function codegen_struct(name, cg) {
print ""
print "export class " name " {"
print cg["fields"] cg["methods"]
print "\tstatic deserialize(r) {"
print "\t\tconst s = new " name "()"
print indent(cg["deserialize"]) "\t\treturn s"
print "\t}"
print "}"
CodegenDeserialize[name] = "\t%s = " name ".deserialize(r)\n"
for (i in cg)
delete cg[i]
}
function codegen_union_tag(d, cg) {
cg["tagtype"] = d["type"]
cg["tagname"] = d["name"]
}
function codegen_union_struct(name, casename, cg, scg, structname) {
append(scg, "methods",
"\n" \
"\tconstructor() {\n" \
"\t\tthis." decapitalize(snaketocamel(cg["tagname"])) \
" = " cg["tagtype"] "." snaketocamel(casename) "\n" \
"\t}\n")
# And thus not all generated structs are present in Types.
structname = name snaketocamel(casename)
codegen_struct(structname, scg)
append(cg, "deserialize",
"\tcase " cg["tagtype"] "." snaketocamel(casename) ":\n" \
"\t{\n" \
indent(sprintf(CodegenDeserialize[structname], "const s")) \
"\t\treturn s\n" \
"\t}\n")
}
function codegen_union(name, cg, tagvar) {
tagvar = decapitalize(snaketocamel(cg["tagname"]))
print ""
print "export function deserialize" name "(r) {"
print sprintf(CodegenDeserialize[cg["tagtype"]], "const " tagvar) \
"\tswitch (" tagvar ") {"
print cg["deserialize"] "\tdefault:"
print "\t\tthrow `Unknown " cg["tagtype"] " (${tagvar})`"
print "\t}"
print "}"
CodegenDeserialize[name] = "\t%s = deserialize" name "(r)\n"
for (i in cg)
delete cg[i]
}
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