Move json and query helpers

This commit is contained in:
jaina heartles 2022-11-25 17:42:58 -08:00
parent 039377f168
commit a28af9e1fe
2 changed files with 1057 additions and 0 deletions

677
src/http/json.zig Normal file
View file

@ -0,0 +1,677 @@
const std = @import("std");
const mem = std.mem;
const Allocator = std.mem.Allocator;
const assert = std.debug.assert;
// This file is largely a copy of std.json
const StreamingParser = std.json.StreamingParser;
const Token = std.json.Token;
const unescapeValidString = std.json.unescapeValidString;
const UnescapeValidStringError = std.json.UnescapeValidStringError;
pub fn parse(comptime T: type, body: []const u8, alloc: std.mem.Allocator) !T {
var tokens = TokenStream.init(body);
const options = ParseOptions{ .allocator = alloc };
const token = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
const r = try parseInternal(T, token, &tokens, options);
errdefer parseFreeInternal(T, r, options);
if (!options.allow_trailing_data) {
if ((try tokens.next()) != null) unreachable;
assert(tokens.i >= tokens.slice.len);
}
return r;
}
pub fn parseFree(value: anytype, alloc: std.mem.Allocator) void {
parseFreeInternal(@TypeOf(value), value, .{ .allocator = alloc });
}
// WARNING: the objects "parse" method must not contain a reference to the original value
fn hasCustomParse(comptime T: type) bool {
if (!std.meta.trait.hasFn("parse")(T)) return false;
if (!@hasDecl(T, "JsonParseAs")) return false;
return true;
}
///// The rest is (modified) from std.json
/// A small wrapper over a StreamingParser for full slices. Returns a stream of json Tokens.
pub const TokenStream = struct {
i: usize,
slice: []const u8,
parser: StreamingParser,
token: ?Token,
pub const Error = StreamingParser.Error || error{UnexpectedEndOfJson};
pub fn init(slice: []const u8) TokenStream {
return TokenStream{
.i = 0,
.slice = slice,
.parser = StreamingParser.init(),
.token = null,
};
}
fn stackUsed(self: *TokenStream) usize {
return self.parser.stack.len + if (self.token != null) @as(usize, 1) else 0;
}
pub fn next(self: *TokenStream) Error!?Token {
if (self.token) |token| {
self.token = null;
return token;
}
var t1: ?Token = undefined;
var t2: ?Token = undefined;
while (self.i < self.slice.len) {
try self.parser.feed(self.slice[self.i], &t1, &t2);
self.i += 1;
if (t1) |token| {
self.token = t2;
return token;
}
}
// Without this a bare number fails, the streaming parser doesn't know the input ended
try self.parser.feed(' ', &t1, &t2);
self.i += 1;
if (t1) |token| {
return token;
} else if (self.parser.complete) {
return null;
} else {
return error.UnexpectedEndOfJson;
}
}
};
/// Checks to see if a string matches what it would be as a json-encoded string
/// Assumes that `encoded` is a well-formed json string
fn encodesTo(decoded: []const u8, encoded: []const u8) bool {
var i: usize = 0;
var j: usize = 0;
while (i < decoded.len) {
if (j >= encoded.len) return false;
if (encoded[j] != '\\') {
if (decoded[i] != encoded[j]) return false;
j += 1;
i += 1;
} else {
const escape_type = encoded[j + 1];
if (escape_type != 'u') {
const t: u8 = switch (escape_type) {
'\\' => '\\',
'/' => '/',
'n' => '\n',
'r' => '\r',
't' => '\t',
'f' => 12,
'b' => 8,
'"' => '"',
else => unreachable,
};
if (decoded[i] != t) return false;
j += 2;
i += 1;
} else {
var codepoint = std.fmt.parseInt(u21, encoded[j + 2 .. j + 6], 16) catch unreachable;
j += 6;
if (codepoint >= 0xD800 and codepoint < 0xDC00) {
// surrogate pair
assert(encoded[j] == '\\');
assert(encoded[j + 1] == 'u');
const low_surrogate = std.fmt.parseInt(u21, encoded[j + 2 .. j + 6], 16) catch unreachable;
codepoint = 0x10000 + (((codepoint & 0x03ff) << 10) | (low_surrogate & 0x03ff));
j += 6;
}
var buf: [4]u8 = undefined;
const len = std.unicode.utf8Encode(codepoint, &buf) catch unreachable;
if (i + len > decoded.len) return false;
if (!mem.eql(u8, decoded[i .. i + len], buf[0..len])) return false;
i += len;
}
}
}
assert(i == decoded.len);
assert(j == encoded.len);
return true;
}
/// parse tokens from a stream, returning `false` if they do not decode to `value`
fn parsesTo(comptime T: type, value: T, tokens: *TokenStream, options: ParseOptions) !bool {
// TODO: should be able to write this function to not require an allocator
const tmp = try parse(T, tokens, options);
defer parseFree(T, tmp, options);
return parsedEqual(tmp, value);
}
/// Returns if a value returned by `parse` is deep-equal to another value
fn parsedEqual(a: anytype, b: @TypeOf(a)) bool {
switch (@typeInfo(@TypeOf(a))) {
.Optional => {
if (a == null and b == null) return true;
if (a == null or b == null) return false;
return parsedEqual(a.?, b.?);
},
.Union => |info| {
if (info.tag_type) |UnionTag| {
const tag_a = std.meta.activeTag(a);
const tag_b = std.meta.activeTag(b);
if (tag_a != tag_b) return false;
inline for (info.fields) |field_info| {
if (@field(UnionTag, field_info.name) == tag_a) {
return parsedEqual(@field(a, field_info.name), @field(b, field_info.name));
}
}
return false;
} else {
unreachable;
}
},
.Array => {
for (a) |e, i|
if (!parsedEqual(e, b[i])) return false;
return true;
},
.Struct => |info| {
inline for (info.fields) |field_info| {
if (!parsedEqual(@field(a, field_info.name), @field(b, field_info.name))) return false;
}
return true;
},
.Pointer => |ptrInfo| switch (ptrInfo.size) {
.One => return parsedEqual(a.*, b.*),
.Slice => {
if (a.len != b.len) return false;
for (a) |e, i|
if (!parsedEqual(e, b[i])) return false;
return true;
},
.Many, .C => unreachable,
},
else => return a == b,
}
unreachable;
}
const ParseOptions = struct {
allocator: ?Allocator = null,
/// Behaviour when a duplicate field is encountered.
duplicate_field_behavior: enum {
UseFirst,
Error,
UseLast,
} = .Error,
/// If false, finding an unknown field returns an error.
ignore_unknown_fields: bool = false,
allow_trailing_data: bool = false,
};
const SkipValueError = error{UnexpectedJsonDepth} || TokenStream.Error;
fn skipValue(tokens: *TokenStream) SkipValueError!void {
const original_depth = tokens.stackUsed();
// Return an error if no value is found
_ = try tokens.next();
if (tokens.stackUsed() < original_depth) return error.UnexpectedJsonDepth;
if (tokens.stackUsed() == original_depth) return;
while (try tokens.next()) |_| {
if (tokens.stackUsed() == original_depth) return;
}
}
fn ParseInternalError(comptime T: type) type {
// `inferred_types` is used to avoid infinite recursion for recursive type definitions.
const inferred_types = [_]type{};
return ParseInternalErrorImpl(T, &inferred_types);
}
fn ParseInternalErrorImpl(comptime T: type, comptime inferred_types: []const type) type {
if (hasCustomParse(T)) {
return ParseInternalError(T.JsonParseAs) || T.ParseError;
}
for (inferred_types) |ty| {
if (T == ty) return error{};
}
switch (@typeInfo(T)) {
.Bool => return error{UnexpectedToken},
.Float, .ComptimeFloat => return error{UnexpectedToken} || std.fmt.ParseFloatError,
.Int, .ComptimeInt => {
return error{ UnexpectedToken, InvalidNumber, Overflow } ||
std.fmt.ParseIntError || std.fmt.ParseFloatError;
},
.Optional => |optionalInfo| {
return ParseInternalErrorImpl(optionalInfo.child, inferred_types ++ [_]type{T});
},
.Enum => return error{ UnexpectedToken, InvalidEnumTag } || std.fmt.ParseIntError ||
std.meta.IntToEnumError || std.meta.IntToEnumError,
.Union => |unionInfo| {
if (unionInfo.tag_type) |_| {
var errors = error{NoUnionMembersMatched};
for (unionInfo.fields) |u_field| {
errors = errors || ParseInternalErrorImpl(u_field.field_type, inferred_types ++ [_]type{T});
}
return errors;
} else {
@compileError("Unable to parse into untagged union '" ++ @typeName(T) ++ "'");
}
},
.Struct => |structInfo| {
var errors = error{
DuplicateJSONField,
UnexpectedEndOfJson,
UnexpectedToken,
UnexpectedValue,
UnknownField,
MissingField,
} || SkipValueError || TokenStream.Error;
for (structInfo.fields) |field| {
errors = errors || ParseInternalErrorImpl(field.field_type, inferred_types ++ [_]type{T});
}
return errors;
},
.Array => |arrayInfo| {
return error{ UnexpectedEndOfJson, UnexpectedToken } || TokenStream.Error ||
UnescapeValidStringError ||
ParseInternalErrorImpl(arrayInfo.child, inferred_types ++ [_]type{T});
},
.Pointer => |ptrInfo| {
var errors = error{AllocatorRequired} || std.mem.Allocator.Error;
switch (ptrInfo.size) {
.One => {
return errors || ParseInternalErrorImpl(ptrInfo.child, inferred_types ++ [_]type{T});
},
.Slice => {
return errors || error{ UnexpectedEndOfJson, UnexpectedToken } ||
ParseInternalErrorImpl(ptrInfo.child, inferred_types ++ [_]type{T}) ||
UnescapeValidStringError || TokenStream.Error;
},
else => @compileError("Unable to parse into type '" ++ @typeName(T) ++ "'"),
}
},
else => return error{},
}
unreachable;
}
fn parseInternal(
comptime T: type,
token: Token,
tokens: *TokenStream,
options: ParseOptions,
) ParseInternalError(T)!T {
if (comptime hasCustomParse(T)) {
const val = try parseInternal(T.JsonParseAs, token, tokens, options);
defer parseFreeInternal(T.JsonParseAs, val, options);
return try T.parse(val);
}
switch (@typeInfo(T)) {
.Bool => {
return switch (token) {
.True => true,
.False => false,
else => error.UnexpectedToken,
};
},
.Float, .ComptimeFloat => {
switch (token) {
.Number => |numberToken| return try std.fmt.parseFloat(T, numberToken.slice(tokens.slice, tokens.i - 1)),
.String => |stringToken| return try std.fmt.parseFloat(T, stringToken.slice(tokens.slice, tokens.i - 1)),
else => return error.UnexpectedToken,
}
},
.Int, .ComptimeInt => {
switch (token) {
.Number => |numberToken| {
if (numberToken.is_integer)
return try std.fmt.parseInt(T, numberToken.slice(tokens.slice, tokens.i - 1), 10);
const float = try std.fmt.parseFloat(f128, numberToken.slice(tokens.slice, tokens.i - 1));
if (@round(float) != float) return error.InvalidNumber;
if (float > std.math.maxInt(T) or float < std.math.minInt(T)) return error.Overflow;
return @floatToInt(T, float);
},
.String => |stringToken| {
return std.fmt.parseInt(T, stringToken.slice(tokens.slice, tokens.i - 1), 10) catch |err| {
switch (err) {
error.Overflow => return err,
error.InvalidCharacter => {
const float = try std.fmt.parseFloat(f128, stringToken.slice(tokens.slice, tokens.i - 1));
if (@round(float) != float) return error.InvalidNumber;
if (float > std.math.maxInt(T) or float < std.math.minInt(T)) return error.Overflow;
return @floatToInt(T, float);
},
}
};
},
else => return error.UnexpectedToken,
}
},
.Optional => |optionalInfo| {
if (token == .Null) {
return null;
} else {
return try parseInternal(optionalInfo.child, token, tokens, options);
}
},
.Enum => |enumInfo| {
switch (token) {
.Number => |numberToken| {
if (!numberToken.is_integer) return error.UnexpectedToken;
const n = try std.fmt.parseInt(enumInfo.tag_type, numberToken.slice(tokens.slice, tokens.i - 1), 10);
return try std.meta.intToEnum(T, n);
},
.String => |stringToken| {
const source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
switch (stringToken.escapes) {
.None => return std.meta.stringToEnum(T, source_slice) orelse return error.InvalidEnumTag,
.Some => {
inline for (enumInfo.fields) |field| {
if (field.name.len == stringToken.decodedLength() and encodesTo(field.name, source_slice)) {
return @field(T, field.name);
}
}
return error.InvalidEnumTag;
},
}
},
else => return error.UnexpectedToken,
}
},
.Union => |unionInfo| {
if (unionInfo.tag_type) |_| {
// try each of the union fields until we find one that matches
inline for (unionInfo.fields) |u_field| {
// take a copy of tokens so we can withhold mutations until success
var tokens_copy = tokens.*;
if (parseInternal(u_field.field_type, token, &tokens_copy, options)) |value| {
tokens.* = tokens_copy;
return @unionInit(T, u_field.name, value);
} else |err| {
// Bubble up error.OutOfMemory
// Parsing some types won't have OutOfMemory in their
// error-sets, for the condition to be valid, merge it in.
if (@as(@TypeOf(err) || error{OutOfMemory}, err) == error.OutOfMemory) return err;
// Bubble up AllocatorRequired, as it indicates missing option
if (@as(@TypeOf(err) || error{AllocatorRequired}, err) == error.AllocatorRequired) return err;
// otherwise continue through the `inline for`
}
}
return error.NoUnionMembersMatched;
} else {
@compileError("Unable to parse into untagged union '" ++ @typeName(T) ++ "'");
}
},
.Struct => |structInfo| {
switch (token) {
.ObjectBegin => {},
else => return error.UnexpectedToken,
}
var r: T = undefined;
var fields_seen = [_]bool{false} ** structInfo.fields.len;
errdefer {
inline for (structInfo.fields) |field, i| {
if (fields_seen[i] and !field.is_comptime) {
parseFreeInternal(field.field_type, @field(r, field.name), options);
}
}
}
while (true) {
switch ((try tokens.next()) orelse return error.UnexpectedEndOfJson) {
.ObjectEnd => break,
.String => |stringToken| {
const key_source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
var child_options = options;
child_options.allow_trailing_data = true;
var found = false;
inline for (structInfo.fields) |field, i| {
// TODO: using switches here segfault the compiler (#2727?)
if ((stringToken.escapes == .None and mem.eql(u8, field.name, key_source_slice)) or (stringToken.escapes == .Some and (field.name.len == stringToken.decodedLength() and encodesTo(field.name, key_source_slice)))) {
// if (switch (stringToken.escapes) {
// .None => mem.eql(u8, field.name, key_source_slice),
// .Some => (field.name.len == stringToken.decodedLength() and encodesTo(field.name, key_source_slice)),
// }) {
if (fields_seen[i]) {
// switch (options.duplicate_field_behavior) {
// .UseFirst => {},
// .Error => {},
// .UseLast => {},
// }
if (options.duplicate_field_behavior == .UseFirst) {
// unconditonally ignore value. for comptime fields, this skips check against default_value
const next_token = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
parseFreeInternal(field.field_type, try parseInternal(field.field_type, next_token, tokens, child_options), child_options);
found = true;
break;
} else if (options.duplicate_field_behavior == .Error) {
return error.DuplicateJSONField;
} else if (options.duplicate_field_behavior == .UseLast) {
if (!field.is_comptime) {
parseFreeInternal(field.field_type, @field(r, field.name), child_options);
}
fields_seen[i] = false;
}
}
if (field.is_comptime) {
if (!try parsesTo(field.field_type, @ptrCast(*const field.field_type, field.default_value.?).*, tokens, child_options)) {
return error.UnexpectedValue;
}
} else {
const next_token = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
@field(r, field.name) = try parseInternal(field.field_type, next_token, tokens, child_options);
}
fields_seen[i] = true;
found = true;
break;
}
}
if (!found) {
if (options.ignore_unknown_fields) {
try skipValue(tokens);
continue;
} else {
return error.UnknownField;
}
}
},
else => return error.UnexpectedToken,
}
}
inline for (structInfo.fields) |field, i| {
if (!fields_seen[i]) {
if (field.default_value) |default_ptr| {
if (!field.is_comptime) {
const default = @ptrCast(*align(1) const field.field_type, default_ptr).*;
@field(r, field.name) = default;
}
} else {
return error.MissingField;
}
}
}
return r;
},
.Array => |arrayInfo| {
switch (token) {
.ArrayBegin => {
var r: T = undefined;
var i: usize = 0;
var child_options = options;
child_options.allow_trailing_data = true;
errdefer {
// Without the r.len check `r[i]` is not allowed
if (r.len > 0) while (true) : (i -= 1) {
parseFreeInternal(arrayInfo.child, r[i], options);
if (i == 0) break;
};
}
while (i < r.len) : (i += 1) {
const next_token = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
r[i] = try parseInternal(arrayInfo.child, next_token, tokens, child_options);
}
const tok = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
switch (tok) {
.ArrayEnd => {},
else => return error.UnexpectedToken,
}
return r;
},
.String => |stringToken| {
if (arrayInfo.child != u8) return error.UnexpectedToken;
var r: T = undefined;
const source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
switch (stringToken.escapes) {
.None => mem.copy(u8, &r, source_slice),
.Some => try unescapeValidString(&r, source_slice),
}
return r;
},
else => return error.UnexpectedToken,
}
},
.Pointer => |ptrInfo| {
const allocator = options.allocator orelse return error.AllocatorRequired;
switch (ptrInfo.size) {
.One => {
const r: T = try allocator.create(ptrInfo.child);
errdefer allocator.destroy(r);
r.* = try parseInternal(ptrInfo.child, token, tokens, options);
return r;
},
.Slice => {
switch (token) {
.ArrayBegin => {
var arraylist = std.ArrayList(ptrInfo.child).init(allocator);
errdefer {
while (arraylist.popOrNull()) |v| {
parseFreeInternal(ptrInfo.child, v, options);
}
arraylist.deinit();
}
while (true) {
const tok = (try tokens.next()) orelse return error.UnexpectedEndOfJson;
switch (tok) {
.ArrayEnd => break,
else => {},
}
try arraylist.ensureUnusedCapacity(1);
const v = try parseInternal(ptrInfo.child, tok, tokens, options);
arraylist.appendAssumeCapacity(v);
}
if (ptrInfo.sentinel) |some| {
const sentinel_value = @ptrCast(*const ptrInfo.child, some).*;
try arraylist.append(sentinel_value);
const output = arraylist.toOwnedSlice();
return output[0 .. output.len - 1 :sentinel_value];
}
return arraylist.toOwnedSlice();
},
.String => |stringToken| {
if (ptrInfo.child != u8) return error.UnexpectedToken;
const source_slice = stringToken.slice(tokens.slice, tokens.i - 1);
const len = stringToken.decodedLength();
const output = try allocator.alloc(u8, len + @boolToInt(ptrInfo.sentinel != null));
errdefer allocator.free(output);
switch (stringToken.escapes) {
.None => mem.copy(u8, output, source_slice),
.Some => try unescapeValidString(output, source_slice),
}
if (ptrInfo.sentinel) |some| {
const char = @ptrCast(*const u8, some).*;
output[len] = char;
return output[0..len :char];
}
return output;
},
else => return error.UnexpectedToken,
}
},
else => @compileError("Unable to parse into type '" ++ @typeName(T) ++ "'"),
}
},
else => @compileError("Unable to parse into type '" ++ @typeName(T) ++ "'"),
}
unreachable;
}
fn ParseError(comptime T: type) type {
return ParseInternalError(T) || error{UnexpectedEndOfJson} || TokenStream.Error;
}
/// Releases resources created by `parse`.
/// Should be called with the same type and `ParseOptions` that were passed to `parse`
fn parseFreeInternal(comptime T: type, value: T, options: ParseOptions) void {
switch (@typeInfo(T)) {
.Bool, .Float, .ComptimeFloat, .Int, .ComptimeInt, .Enum => {},
.Optional => {
if (value) |v| {
return parseFreeInternal(@TypeOf(v), v, options);
}
},
.Union => |unionInfo| {
if (unionInfo.tag_type) |UnionTagType| {
inline for (unionInfo.fields) |u_field| {
if (value == @field(UnionTagType, u_field.name)) {
parseFreeInternal(u_field.field_type, @field(value, u_field.name), options);
break;
}
}
} else {
unreachable;
}
},
.Struct => |structInfo| {
inline for (structInfo.fields) |field| {
if (!field.is_comptime) {
parseFreeInternal(field.field_type, @field(value, field.name), options);
}
}
},
.Array => |arrayInfo| {
for (value) |v| {
parseFreeInternal(arrayInfo.child, v, options);
}
},
.Pointer => |ptrInfo| {
const allocator = options.allocator orelse unreachable;
switch (ptrInfo.size) {
.One => {
parseFreeInternal(ptrInfo.child, value.*, options);
allocator.destroy(value);
},
.Slice => {
for (value) |v| {
parseFreeInternal(ptrInfo.child, v, options);
}
allocator.free(value);
},
else => unreachable,
}
},
else => unreachable,
}
}

380
src/http/query.zig Normal file
View file

@ -0,0 +1,380 @@
const std = @import("std");
const QueryIter = @import("util").QueryIter;
/// Parses a set of query parameters described by the struct `T`.
///
/// To specify query parameters, provide a struct similar to the following:
/// ```
/// struct {
/// foo: bool = false,
/// bar: ?[]const u8 = null,
/// baz: usize = 10,
/// qux: enum { quux, snap } = .quux,
/// }
/// ```
///
/// This will allow it to parse a query string like the following:
/// `?foo&bar=abc&qux=snap`
///
/// Every parameter must have a default value that will be used when the
/// parameter is not provided, and parameter keys.
/// Numbers are parsed from their string representations, and a parameter
/// provided in the query string without a value is parsed either as a bool
/// `true` flag or as `null` depending on the type of its param.
///
/// Parameter types supported:
/// - []const u8
/// - numbers (both integer and float)
/// + Numbers are parsed in base 10
/// - bool
/// + See below for detals
/// - exhaustive enums
/// + Enums are treated as strings with values equal to the enum fields
/// - ?F (where isScalar(F) and F != bool)
/// - Any type that implements:
/// + pub fn parse([]const u8) !F
///
/// Boolean Parameters:
/// The following query strings will all parse a `true` value for the
/// parameter `foo: bool = false`:
/// - `?foo`
/// - `?foo=true`
/// - `?foo=t`
/// - `?foo=yes`
/// - `?foo=y`
/// - `?foo=1`
/// And the following query strings all parse a `false` value:
/// - `?`
/// - `?foo=false`
/// - `?foo=f`
/// - `?foo=no`
/// - `?foo=n`
/// - `?foo=0`
///
/// Compound Types:
/// Compound (struct) types are also supported, with the parameter key
/// for its parameters consisting of the struct's field + '.' + parameter
/// field. For example:
/// ```
/// struct {
/// foo: struct {
/// baz: usize = 0,
/// } = .{},
/// }
/// ```
/// Would be used to parse a query string like
/// `?foo.baz=12345`
///
/// Compound types cannot currently be nullable, and must be structs.
///
/// TODO: values are currently case-sensitive, and are not url-decoded properly.
/// This should be fixed.
pub fn parseQuery(alloc: std.mem.Allocator, comptime T: type, query: []const u8) !T {
if (comptime !std.meta.trait.isContainer(T)) @compileError("T must be a struct");
var iter = QueryIter.from(query);
var fields = Intermediary(T){};
while (iter.next()) |pair| {
// TODO: Hash map
inline for (std.meta.fields(Intermediary(T))) |field| {
if (std.ascii.eqlIgnoreCase(field.name[2..], pair.key)) {
@field(fields, field.name) = if (pair.value) |v| .{ .value = v } else .{ .no_value = {} };
break;
}
} else std.log.debug("unknown param {s}", .{pair.key});
}
return (try parse(alloc, T, "", "", fields)) orelse error.NoQuery;
}
fn decodeString(alloc: std.mem.Allocator, val: []const u8) ![]const u8 {
var list = try std.ArrayList(u8).initCapacity(alloc, val.len);
errdefer list.deinit();
var idx: usize = 0;
while (idx < val.len) : (idx += 1) {
if (val[idx] != '%') {
try list.append(val[idx]);
} else {
if (val.len < idx + 2) return error.InvalidEscape;
const buf = [2]u8{ val[idx + 1], val[idx + 2] };
idx += 2;
const ch = try std.fmt.parseInt(u8, &buf, 16);
try list.append(ch);
}
}
return list.toOwnedSlice();
}
fn parseScalar(alloc: std.mem.Allocator, comptime T: type, comptime name: []const u8, fields: anytype) !?T {
const param = @field(fields, name);
return switch (param) {
.not_specified => null,
.no_value => try parseQueryValue(alloc, T, null),
.value => |v| try parseQueryValue(alloc, T, v),
};
}
fn parse(
alloc: std.mem.Allocator,
comptime T: type,
comptime prefix: []const u8,
comptime name: []const u8,
fields: anytype,
) !?T {
if (comptime isScalar(T)) return parseScalar(alloc, T, prefix ++ "." ++ name, fields);
switch (@typeInfo(T)) {
.Union => |info| {
var result: ?T = null;
inline for (info.fields) |field| {
const F = field.field_type;
const maybe_value = try parse(alloc, F, prefix, field.name, fields);
if (maybe_value) |value| {
if (result != null) return error.DuplicateUnionField;
result = @unionInit(T, field.name, value);
}
}
std.log.debug("{any}", .{result});
return result;
},
.Struct => |info| {
var result: T = undefined;
var fields_specified: usize = 0;
inline for (info.fields) |field| {
const F = field.field_type;
var maybe_value: ?F = null;
if (try parse(alloc, F, prefix ++ "." ++ name, field.name, fields)) |v| {
maybe_value = v;
} else if (field.default_value) |default| {
if (comptime @sizeOf(F) != 0) {
maybe_value = @ptrCast(*const F, @alignCast(@alignOf(F), default)).*;
} else {
maybe_value = std.mem.zeroes(F);
}
}
if (maybe_value) |v| {
fields_specified += 1;
@field(result, field.name) = v;
}
}
if (fields_specified == 0) {
return null;
} else if (fields_specified != info.fields.len) {
std.log.debug("{} {s} {s}", .{ T, prefix, name });
return error.PartiallySpecifiedStruct;
} else {
return result;
}
},
// Only applies to non-scalar optionals
.Optional => |info| return try parse(alloc, info.child, prefix, name, fields),
else => @compileError("tmp"),
}
}
fn recursiveFieldPaths(comptime T: type, comptime prefix: []const u8) []const []const u8 {
comptime {
if (std.meta.trait.is(.Optional)(T)) return recursiveFieldPaths(std.meta.Child(T), prefix);
var fields: []const []const u8 = &.{};
for (std.meta.fields(T)) |f| {
const full_name = prefix ++ f.name;
if (isScalar(f.field_type)) {
fields = fields ++ @as([]const []const u8, &.{full_name});
} else {
const field_prefix = if (@typeInfo(f.field_type) == .Union) prefix else full_name ++ ".";
fields = fields ++ recursiveFieldPaths(f.field_type, field_prefix);
}
}
return fields;
}
}
const QueryParam = union(enum) {
not_specified: void,
no_value: void,
value: []const u8,
};
fn Intermediary(comptime T: type) type {
const field_names = recursiveFieldPaths(T, "..");
var fields: [field_names.len]std.builtin.Type.StructField = undefined;
for (field_names) |name, i| fields[i] = .{
.name = name,
.field_type = QueryParam,
.default_value = &QueryParam{ .not_specified = {} },
.is_comptime = false,
.alignment = @alignOf(QueryParam),
};
return @Type(.{ .Struct = .{
.layout = .Auto,
.fields = &fields,
.decls = &.{},
.is_tuple = false,
} });
}
fn parseQueryValue(alloc: std.mem.Allocator, comptime T: type, value: ?[]const u8) !T {
const is_optional = comptime std.meta.trait.is(.Optional)(T);
// If param is present, but without an associated value
if (value == null) {
return if (is_optional)
null
else if (T == bool)
true
else
error.InvalidValue;
}
return try parseQueryValueNotNull(alloc, if (is_optional) std.meta.Child(T) else T, value.?);
}
const bool_map = std.ComptimeStringMap(bool, .{
.{ "true", true },
.{ "t", true },
.{ "yes", true },
.{ "y", true },
.{ "1", true },
.{ "false", false },
.{ "f", false },
.{ "no", false },
.{ "n", false },
.{ "0", false },
});
fn parseQueryValueNotNull(alloc: std.mem.Allocator, comptime T: type, value: []const u8) !T {
const decoded = try decodeString(alloc, value);
errdefer alloc.free(decoded);
if (comptime std.meta.trait.isZigString(T)) return decoded;
const result = if (comptime std.meta.trait.isIntegral(T))
try std.fmt.parseInt(T, decoded, 0)
else if (comptime std.meta.trait.isFloat(T))
try std.fmt.parseFloat(T, decoded)
else if (comptime std.meta.trait.is(.Enum)(T))
std.meta.stringToEnum(T, decoded) orelse return error.InvalidEnumValue
else if (T == bool)
bool_map.get(value) orelse return error.InvalidBool
else if (comptime std.meta.trait.hasFn("parse")(T))
try T.parse(value)
else
@compileError("Invalid type " ++ @typeName(T));
alloc.free(decoded);
return result;
}
fn isScalar(comptime T: type) bool {
if (comptime std.meta.trait.isZigString(T)) return true;
if (comptime std.meta.trait.isIntegral(T)) return true;
if (comptime std.meta.trait.isFloat(T)) return true;
if (comptime std.meta.trait.is(.Enum)(T)) return true;
if (T == bool) return true;
if (comptime std.meta.trait.hasFn("parse")(T)) return true;
if (comptime std.meta.trait.is(.Optional)(T) and isScalar(std.meta.Child(T))) return true;
return false;
}
pub fn formatQuery(params: anytype, writer: anytype) !void {
try format("", "", params, writer);
}
fn urlFormatString(writer: anytype, val: []const u8) !void {
for (val) |ch| {
const printable = switch (ch) {
'0'...'9', 'a'...'z', 'A'...'Z' => true,
'-', '.', '_', '~', ':', '@', '!', '$', '&', '\'', '(', ')', '*', '+', ',', ';', '=' => true,
else => false,
};
try if (printable) writer.writeByte(ch) else std.fmt.format(writer, "%{x:0>2}", .{ch});
}
}
fn formatScalar(comptime name: []const u8, val: anytype, writer: anytype) !void {
const T = @TypeOf(val);
if (comptime std.meta.trait.is(.Optional)(T)) {
return if (val) |v| formatScalar(name, v, writer) else {};
}
try urlFormatString(writer, name);
try writer.writeByte('=');
if (comptime std.meta.trait.isZigString(T)) {
try urlFormatString(writer, val);
} else try switch (@typeInfo(T)) {
.Enum => urlFormatString(writer, @tagName(val)),
else => std.fmt.format(writer, "{}", .{val}),
};
try writer.writeByte('&');
}
fn format(comptime prefix: []const u8, comptime name: []const u8, params: anytype, writer: anytype) !void {
const T = @TypeOf(params);
const eff_prefix = if (prefix.len == 0) "" else prefix ++ ".";
if (comptime isScalar(T)) return formatScalar(eff_prefix ++ name, params, writer);
switch (@typeInfo(T)) {
.Struct => {
inline for (std.meta.fields(T)) |field| {
const val = @field(params, field.name);
try format(eff_prefix ++ name, field.name, val, writer);
}
},
.Union => {
inline for (std.meta.fields(T)) |field| {
const tag = @field(std.meta.Tag(T), field.name);
const tag_name = field.name;
if (@as(std.meta.Tag(T), params) == tag) {
const val = @field(params, tag_name);
try format(prefix, tag_name, val, writer);
}
}
},
.Optional => {
if (params) |p| try format(prefix, name, p, writer);
},
else => @compileError("Unsupported query type"),
}
}
test {
const TestQuery = struct {
int: usize = 3,
boolean: bool = false,
str_enum: ?enum { foo, bar } = null,
};
try std.testing.expectEqual(TestQuery{
.int = 3,
.boolean = false,
.str_enum = null,
}, try parseQuery(TestQuery, ""));
try std.testing.expectEqual(TestQuery{
.int = 5,
.boolean = true,
.str_enum = .foo,
}, try parseQuery(TestQuery, "?int=5&boolean=yes&str_enum=foo"));
}