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Author SHA1 Message Date
torque
96b950755b config: migrate flow parser into the main parser object 
I think I am actually going to make this a method of the ParserState
struct soon so lol check out my freaking code churn. But here we are.
 2023-09-23 13:29:49 -07:00
torque
9c866970f8 config: remove some duplication in the parser 
There's still a fair amount lurking in here, but I believe this logic
is sound. Rather than duplicating the map/list logic under the
opposing key, we set the logic up to use the second loop around
(this is was how dedents worked, and now it also works for indents).

I'm not convinced this is as easy to follow, and it did lead me to add
some additional unreachables to the code, which should maybe be turned
into error returns instead. It does reduce the odds of a code change
missing a copied instance, which I think is a good thing.
 2023-09-23 01:07:04 -07:00
torque
47f4a1c479 config: dupe map keys 
I didn't do an exhaustive search, but it seems that the managed
hashmaps only allocates space for the structure of the map itself, not
its keys or values. This mostly makes sense, but it also means that
this was only working due to the fact that I am currently not freeing
the input buffer until after iterating through the parse result.

Looking through this, I'm also reasonably surprised by how many times
this is assigned in the normal parsing vs the flow parsing. There is a
lot more repetition in the code of the normal parser, I think because
it does not have a granular state machine. It may be worth revisiting
the structure to see if a more detailed state machine, like the one
used for parsing the flow-style objects, would reduce the amount of
code repetition here. I suspect it certainly could be better than it
currently is, since it seems unlikely that there really are four
different scenarios where we need to be parsing a dictionary key.
Taking a quick glance at it, it looks like I could be taking better
advantage of the flipflop loop on indent as well as dedent. This might
be a bit less efficient due to essentially being less loop unrolling,
but it would also potentially make more maintainable code by having
less manual repetition.
 2023-09-22 01:01:46 -07:00
torque
e9cf908b61 config: use std.StringArrayHashMap for the map type 
As I was thinking about this, I realized that data serialization is
much more of a bear than deserialization. Or, more accurately, trying
to make stable round trip serialization a goal puts heavier demands on
deserialization, including preserving input order.

I think there may be a mountain hiding under this molehill, though,
because the goals of having a format that is designed to be
handwritten and also machine written are at odds with each other.
Right now, the parser does not preserve comments at all. But even if
we did (they could easily become a special type of string), comment
indentation is ignored. Comments are not directly a child of any other
part of the document, they're awkward text that exists interspersed
throughout it.

With the current design, there are some essentially unsolvable
problems, like comments interspersed throughout multiline strings. The
string is processed into a single object in the output, so there can't
be weird magic data interleaved with it because it loses the concept
of being interleaved entirely (this is a bigger issue for space
strings, which don't even preserve a unique way to reserialize them.
Line strings at least contain a character (the newline) that can
appear nowhere else but at a break in the string). Obviously this isn't
technically impossible, but it would require a change to the way that
values are modeled.

And even if we did take the approach of associating a comment with,
say, the value that follows it (which I think is a reasonable thing to
do, ignoring the interleaved comment situation described above), if
software reads in data, changes it, and writes it back out, how do we
account for deleted items? Does the comment get deleted with the item?
Does it become a dangling comment that just gets shoved somewhere in
the document? How are comments that come after everything else in the
document handled?

From a pure data perspective, it's fairly obvious why JSON omits
comments: they're trivial to parse, but there's not a strategy for
emitting them that will always be correct, especially in a format that
doesn't give a hoot about linebreaks. It may be interesting to look at
fancy TOML (barf) parsers to see how they handle comments, though I
assume the general technique is to store their row position in the
original document and track when a line is added or removed.

Ultimately, I think the use case of a format to be written by humans
and read by computers is still useful. That's my intended use case for
this and why I started it, but its application as a configuration file
format is probably hamstrung muchly by software not being able to
write it back. On the other hand, there's a lot of successful software
I use where the config files are not written directly by the software
at all, so maybe it's entirely fine to declare this as being out of
scope and not worrying about it further. At the very least it's almost
certainly less of an issue than erroring on carriage returns. Also the
fact that certain keys are simply unrepresentable.

As a side note, I guess what they say about commit message length being
inversely proportional to the change length is true. Hope you enjoyed
the blog over this 5 character change.
 2023-09-22 01:01:46 -07:00
torque
6415571d01 config: refactor LineTokenizer to use an internal line buffer 
The goal here is to support a streaming parser. However, I did decide
the leave the flow item parser state machine as fully buffered
(i.e. not streaming). This is not JSON and in general documents should
be many, shorter lines, so this buffering strategy should work
reasonably well. I have not actually tried the streaming
implementation of this, yet.
 2023-09-22 01:00:17 -07:00
torque
ab580fa80a config: differentiate fields in Value 
This makes handling Value very slightly more work, but it provides
useful metadata that can be used to perform better conversion and
serialization.

The motivation behind the "scalar" type is that in general, only
scalars can be coerced to other types. For example, a scalar `null`
and a string `> null` have the same in-memory representation. If they
are treated identically, this precludes unambiguously converting an
optional string whose contents are "null". With the two disambiguated,
we can choose to convert `null` to the null object and `> null` to a
string of contents "null". This ambiguity does not necessary exist for
the standard boolean values `true` and `false`, but it does allow the
conversion to be more strict, and it will theoretically result in
documents that read more naturally.

The motivation behind exposing flow_list and flow_map is that it will
allow preserving document formatting round trip (well, this isn't
strictly true: single line explicit strings neither remember whether
they were line strings or space strings, and they don't remember if
they were indented. However, that is much less information to lose).

The following formulations will parse to the same indistinguishable
value:

  key: > value
  key:
    > value
  key: | value
  key:
    | value

I think that's okay. It's a lot easier to chose a canonical form for
this case than it is for a map/list without any hints regarding its
origin.
 2023-09-22 01:00:17 -07:00
1 changed files with 301 additions and 394 deletions
Expand all files Collapse all files

695
src/config.zig
View File

@@ -566,8 +566,10 @@ pub const Parser = struct {
EmptyDocument,
DuplicateKey,
BadMapEntry,
BadState,
BadToken,
Fail,
} || LineTokenizer(FixedLineBuffer).Error || FlowParser.Error || std.mem.Allocator.Error;
} || LineTokenizer(FixedLineBuffer).Error || std.mem.Allocator.Error;
pub const DuplicateKeyBehavior = enum {
use_first,
@@ -679,11 +681,11 @@ pub const Parser = struct {
state = .value;
},
.flow_list => |str| {
document.root = try parseFlowList(arena_alloc, str, self.dupe_behavior);
document.root = try parseFlow(arena_alloc, str, .flow_list, self.dupe_behavior);
state = .done;
},
.flow_map => |str| {
document.root = try parseFlowMap(arena_alloc, str, self.dupe_behavior);
document.root = try parseFlow(arena_alloc, str, .flow_map, self.dupe_behavior);
state = .done;
},
},
@@ -705,11 +707,11 @@ pub const Parser = struct {
state = .value;
},
.flow_list => |str| {
try document.root.list.append(try parseFlowList(arena_alloc, str, self.dupe_behavior));
try document.root.list.append(try parseFlow(arena_alloc, str, .flow_list, self.dupe_behavior));
state = .value;
},
.flow_map => |str| {
try document.root.list.append(try parseFlowMap(arena_alloc, str, self.dupe_behavior));
try document.root.list.append(try parseFlow(arena_alloc, str, .flow_map, self.dupe_behavior));
state = .value;
},
}
@@ -743,11 +745,11 @@ pub const Parser = struct {
state = .value;
},
.flow_list => |str| {
try document.root.map.put(pair.key, try parseFlowList(arena_alloc, str, self.dupe_behavior));
try document.root.map.put(pair.key, try parseFlow(arena_alloc, str, .flow_list, self.dupe_behavior));
state = .value;
},
.flow_map => |str| {
try document.root.map.put(pair.key, try parseFlowMap(arena_alloc, str, self.dupe_behavior));
try document.root.map.put(pair.key, try parseFlow(arena_alloc, str, .flow_map, self.dupe_behavior));
state = .value;
},
}
@@ -757,7 +759,7 @@ pub const Parser = struct {
.value => switch (stack.getLast().*) {
// these three states are never reachable here. flow_list and
// flow_map are parsed with a separate state machine. These
// value tyeps can only be present by themselves as the first
// value types can only be present by themselves as the first
// line of the document, in which case the document consists
// only of that single line: this parser jumps immediately into
// the .done state, bypassing the .value state in which this
@@ -799,7 +801,7 @@ pub const Parser = struct {
//
// the first line here creates the expect_shift, but the second line
// is a valid continuation of the list despite not being indented
if (expect_shift == .indent and line.indent != .indent)
if (!flop and (expect_shift == .indent and line.indent != .indent))
try list.append(Value.newScalar(arena_alloc));
// Consider:
@@ -833,52 +835,38 @@ pub const Parser = struct {
switch (in_line) {
.empty => unreachable,
.scalar => |str| try list.append(try Value.fromScalar(arena_alloc, str)),
.flow_list => |str| try list.append(try parseFlowList(arena_alloc, str, self.dupe_behavior)),
.flow_map => |str| try list.append(try parseFlowMap(arena_alloc, str, self.dupe_behavior)),
.flow_list => |str| try list.append(try parseFlow(arena_alloc, str, .flow_list, self.dupe_behavior)),
.flow_map => |str| try list.append(try parseFlow(arena_alloc, str, .flow_map, self.dupe_behavior)),
.line_string, .space_string => |str| {
// string pushes the stack
const new_string = try appendListGetValue(list, try Value.fromString(arena_alloc, str));
try stack.append(new_string);
try new_string.string.append(in_line.lineEnding());
try stack.append(new_string);
expect_shift = .none;
},
}
},
.list_item => |value| {
switch (line.indent) {
// for dedent, the stack has already been popped, so this should be fine
.none, .dedent => {
expect_shift = .none;
switch (value) {
.empty => expect_shift = .indent,
.scalar => |str| try list.append(try Value.fromScalar(arena_alloc, str)),
.line_string, .space_string => |str| try list.append(try Value.fromString(arena_alloc, str)),
.flow_list => |str| try list.append(try parseFlowList(arena_alloc, str, self.dupe_behavior)),
.flow_map => |str| try list.append(try parseFlowMap(arena_alloc, str, self.dupe_behavior)),
}
},
// a new list is being created
.indent => {
if (expect_shift != .indent)
return error.UnexpectedIndent;
if (flop or (line.indent == .none or line.indent == .dedent)) {
expect_shift = .none;
switch (value) {
.empty => expect_shift = .indent,
.scalar => |str| try list.append(try Value.fromScalar(arena_alloc, str)),
.line_string, .space_string => |str| try list.append(try Value.fromString(arena_alloc, str)),
.flow_list => |str| try list.append(try parseFlow(arena_alloc, str, .flow_list, self.dupe_behavior)),
.flow_map => |str| try list.append(try parseFlow(arena_alloc, str, .flow_map, self.dupe_behavior)),
}
} else if (line.indent == .indent) {
if (expect_shift != .indent) return error.UnexpectedIndent;
const new_list = try appendListGetValue(list, Value.newList(arena_alloc));
try stack.append(new_list);
expect_shift = .none;
switch (value) {
.empty => expect_shift = .indent,
.scalar => |str| try new_list.list.append(try Value.fromScalar(arena_alloc, str)),
.line_string, .space_string => |str| try new_list.list.append(try Value.fromString(arena_alloc, str)),
.flow_list => |str| try new_list.list.append(try parseFlowList(arena_alloc, str, self.dupe_behavior)),
.flow_map => |str| try new_list.list.append(try parseFlowMap(arena_alloc, str, self.dupe_behavior)),
}
},
}
const new_list = try appendListGetValue(list, Value.newList(arena_alloc));
try stack.append(new_list);
expect_shift = .none;
continue :flipflop;
} else unreachable;
},
.map_item => |pair| {
.map_item => {
// this prong cannot be hit on dedent in a valid way.
//
// -
@@ -894,17 +882,7 @@ pub const Parser = struct {
const new_map = try appendListGetValue(list, Value.newMap(arena_alloc));
try stack.append(new_map);
expect_shift = .none;
switch (pair.val) {
.empty => {
dangling_key = try arena_alloc.dupe(u8, pair.key);
expect_shift = .indent;
},
.scalar => |str| try new_map.map.put(pair.key, try Value.fromScalar(arena_alloc, str)),
.line_string, .space_string => |str| try new_map.map.put(pair.key, try Value.fromString(arena_alloc, str)),
.flow_list => |str| try new_map.map.put(pair.key, try parseFlowList(arena_alloc, str, self.dupe_behavior)),
.flow_map => |str| try new_map.map.put(pair.key, try parseFlowMap(arena_alloc, str, self.dupe_behavior)),
}
continue :flipflop;
},
}
},
@@ -916,7 +894,7 @@ pub const Parser = struct {
//
// the first line here creates the expect_shift, but the second line
// is a valid continuation of the map despite not being indented
if (expect_shift == .indent and line.indent != .indent) {
if (!flop and (expect_shift == .indent and line.indent != .indent)) {
try putMap(
map,
dangling_key orelse return error.Fail,
@@ -948,9 +926,9 @@ pub const Parser = struct {
switch (in_line) {
.empty => unreachable,
.scalar => |str| try putMap(map, dangling_key.?, try Value.fromScalar(arena_alloc, str), self.dupe_behavior),
.flow_list => |str| try putMap(map, dangling_key.?, try parseFlowList(arena_alloc, str, self.dupe_behavior), self.dupe_behavior),
.flow_list => |str| try putMap(map, dangling_key.?, try parseFlow(arena_alloc, str, .flow_list, self.dupe_behavior), self.dupe_behavior),
.flow_map => |str| {
try putMap(map, dangling_key.?, try parseFlowMap(arena_alloc, str, self.dupe_behavior), self.dupe_behavior);
try putMap(map, dangling_key.?, try parseFlow(arena_alloc, str, .flow_map, self.dupe_behavior), self.dupe_behavior);
},
.line_string, .space_string => |str| {
// string pushes the stack
@@ -963,7 +941,7 @@ pub const Parser = struct {
dangling_key = null;
},
.list_item => |value| {
.list_item => {
// this prong cannot be hit on dedent in a valid way.
//
// map:
@@ -978,50 +956,30 @@ pub const Parser = struct {
const new_list = try putMapGetValue(map, dangling_key.?, Value.newList(arena_alloc), self.dupe_behavior);
try stack.append(new_list);
dangling_key = null;
expect_shift = .none;
switch (value) {
.empty => expect_shift = .indent,
.scalar => |str| try new_list.list.append(try Value.fromScalar(arena_alloc, str)),
.line_string, .space_string => |str| try new_list.list.append(try Value.fromString(arena_alloc, str)),
.flow_list => |str| try new_list.list.append(try parseFlowList(arena_alloc, str, self.dupe_behavior)),
.flow_map => |str| try new_list.list.append(try parseFlowMap(arena_alloc, str, self.dupe_behavior)),
}
continue :flipflop;
},
.map_item => |pair| {
expect_shift = .none;
switch (line.indent) {
// for dedent, the stack has already been popped, so this should be fine
.none, .dedent => switch (pair.val) {
if (flop or (line.indent == .none or line.indent == .dedent)) {
expect_shift = .none;
switch (pair.val) {
.empty => {
expect_shift = .indent;
dangling_key = try arena_alloc.dupe(u8, pair.key);
},
.scalar => |str| try putMap(map, pair.key, try Value.fromScalar(arena_alloc, str), self.dupe_behavior),
.line_string, .space_string => |str| try putMap(map, pair.key, try Value.fromString(arena_alloc, str), self.dupe_behavior),
.flow_list => |str| try putMap(map, pair.key, try parseFlowList(arena_alloc, str, self.dupe_behavior), self.dupe_behavior),
.flow_map => |str| try putMap(map, pair.key, try parseFlowMap(arena_alloc, str, self.dupe_behavior), self.dupe_behavior),
},
// a new map is being created
.indent => {
if (expect_shift != .indent or dangling_key == null) return error.UnexpectedValue;
.flow_list => |str| try putMap(map, pair.key, try parseFlow(arena_alloc, str, .flow_list, self.dupe_behavior), self.dupe_behavior),
.flow_map => |str| try putMap(map, pair.key, try parseFlow(arena_alloc, str, .flow_map, self.dupe_behavior), self.dupe_behavior),
}
} else if (line.indent == .indent) {
if (expect_shift != .indent or dangling_key == null) return error.UnexpectedValue;
const new_map = try putMapGetValue(map, dangling_key.?, Value.newMap(arena_alloc), self.dupe_behavior);
try stack.append(new_map);
dangling_key = null;
switch (pair.val) {
.empty => {
expect_shift = .indent;
dangling_key = try arena_alloc.dupe(u8, pair.key);
},
.scalar => |str| try new_map.map.put(pair.key, try Value.fromScalar(arena_alloc, str)),
.line_string, .space_string => |str| try new_map.map.put(pair.key, try Value.fromString(arena_alloc, str)),
.flow_list => |str| try new_map.map.put(pair.key, try parseFlowList(arena_alloc, str, self.dupe_behavior)),
.flow_map => |str| try new_map.map.put(pair.key, try parseFlowMap(arena_alloc, str, self.dupe_behavior)),
}
},
}
const new_map = try putMapGetValue(map, dangling_key.?, Value.newMap(arena_alloc), self.dupe_behavior);
try stack.append(new_map);
dangling_key = null;
continue :flipflop;
} else unreachable;
},
}
},
@@ -1057,18 +1015,261 @@ pub const Parser = struct {
return document;
}
fn parseFlowList(alloc: std.mem.Allocator, contents: []const u8, dupe_behavior: DuplicateKeyBehavior) Error!Value {
var parser = try FlowParser.initList(alloc, contents);
defer parser.deinit();
const FlowStackItem = struct {
value: *Value,
// lists need this. maps do also for keys and values.
item_start: usize = 0,
};
return try parser.parse(dupe_behavior);
const FlowStack: type = std.ArrayList(FlowStackItem);
inline fn getStackTip(stack: FlowStack) Error!*FlowStackItem {
if (stack.items.len == 0) return error.BadState;
return &stack.items[stack.items.len - 1];
}
fn parseFlowMap(alloc: std.mem.Allocator, contents: []const u8, dupe_behavior: DuplicateKeyBehavior) Error!Value {
var parser = try FlowParser.initMap(alloc, contents);
defer parser.deinit();
inline fn setStackItemStart(stack: FlowStack, start: usize) Error!void {
if (stack.items.len == 0) return error.BadState;
stack.items[stack.items.len - 1].item_start = start;
}
return try parser.parse(dupe_behavior);
inline fn popStack(stack: *FlowStack) Error!FlowParseState {
if (stack.popOrNull() == null)
return error.BadState;
const parent = stack.getLastOrNull() orelse return .done;
return switch (parent.value.*) {
.flow_list => .want_list_separator,
.flow_map => .want_map_separator,
else => return error.BadState,
};
}
const FlowParseState = enum {
want_list_item,
consuming_list_item,
want_list_separator,
want_map_key,
consuming_map_key,
want_map_value,
consuming_map_value,
want_map_separator,
done,
};
pub fn parseFlow(
alloc: std.mem.Allocator,
contents: []const u8,
root_type: Value.TagType,
dupe_behavior: DuplicateKeyBehavior,
) Error!Value {
// prime the stack:
var root: Value = switch (root_type) {
.flow_list => Value.newFlowList(alloc),
.flow_map => Value.newFlowMap(alloc),
else => return error.BadState,
};
var state: FlowParseState = switch (root_type) {
.flow_list => .want_list_item,
.flow_map => .want_map_key,
else => unreachable,
};
var stack = try FlowStack.initCapacity(alloc, 1);
stack.appendAssumeCapacity(.{ .value = &root });
var dangling_key: ?[]const u8 = null;
charloop: for (contents, 0..) |char, idx| {
switch (state) {
.want_list_item => switch (char) {
' ', '\t' => continue :charloop,
',' => {
// empty value
const tip = try getStackTip(stack);
try tip.value.flow_list.append(Value.newScalar(alloc));
tip.item_start = idx + 1;
},
'{' => {
const tip = try getStackTip(stack);
const new_map = try Parser.appendListGetValue(
&tip.value.flow_list,
Value.newFlowMap(alloc),
);
tip.item_start = idx;
try stack.append(.{ .value = new_map });
state = .want_map_key;
},
'[' => {
const tip = try getStackTip(stack);
const new_list = try Parser.appendListGetValue(
&tip.value.flow_list,
Value.newFlowList(alloc),
);
tip.item_start = idx;
try stack.append(.{ .value = new_list, .item_start = idx + 1 });
state = .want_list_item;
},
']' => {
const finished = stack.getLastOrNull() orelse return error.BadState;
if (finished.value.flow_list.items.len > 0 or idx > finished.item_start)
try finished.value.flow_list.append(Value.newScalar(alloc));
state = try popStack(&stack);
},
else => {
try setStackItemStart(stack, idx);
state = .consuming_list_item;
},
},
.consuming_list_item => switch (char) {
',' => {
const tip = try getStackTip(stack);
try tip.value.flow_list.append(
try Value.fromScalar(alloc, contents[tip.item_start..idx]),
);
tip.item_start = idx + 1;
state = .want_list_item;
},
']' => {
const finished = stack.getLastOrNull() orelse return error.BadState;
try finished.value.flow_list.append(
try Value.fromScalar(alloc, contents[finished.item_start..idx]),
);
state = try popStack(&stack);
},
else => continue :charloop,
},
.want_list_separator => switch (char) {
' ', '\t' => continue :charloop,
',' => {
try setStackItemStart(stack, idx);
state = .want_list_item;
},
']' => state = try popStack(&stack),
else => return error.BadToken,
},
.want_map_key => switch (char) {
' ', '\t' => continue :charloop,
// forbid these characters so that flow dictionary keys cannot start
// with characters that regular dictionary keys cannot start with
// (even though they're unambiguous in this specific context).
'{', '[', '#', '-', '>', '|', ',' => return error.BadToken,
':' => {
// we have an empty map key
dangling_key = "";
state = .want_map_value;
},
'}' => state = try popStack(&stack),
else => {
try setStackItemStart(stack, idx);
state = .consuming_map_key;
},
},
.consuming_map_key => switch (char) {
':' => {
const tip = try getStackTip(stack);
dangling_key = try alloc.dupe(u8, contents[tip.item_start..idx]);
state = .want_map_value;
},
else => continue :charloop,
},
.want_map_value => switch (char) {
' ', '\t' => continue :charloop,
',' => {
const tip = try getStackTip(stack);
try Parser.putMap(
&tip.value.flow_map,
dangling_key.?,
Value.newScalar(alloc),
dupe_behavior,
);
dangling_key = null;
state = .want_map_key;
},
'[' => {
const tip = try getStackTip(stack);
const new_list = try Parser.putMapGetValue(
&tip.value.flow_map,
dangling_key.?,
Value.newFlowList(alloc),
dupe_behavior,
);
try stack.append(.{ .value = new_list, .item_start = idx + 1 });
dangling_key = null;
state = .want_list_item;
},
'{' => {
const tip = try getStackTip(stack);
const new_map = try Parser.putMapGetValue(
&tip.value.flow_map,
dangling_key.?,
Value.newFlowMap(alloc),
dupe_behavior,
);
try stack.append(.{ .value = new_map });
dangling_key = null;
state = .want_map_key;
},
'}' => {
// the value is an empty string and this map is closed
const tip = try getStackTip(stack);
try Parser.putMap(
&tip.value.flow_map,
dangling_key.?,
Value.newScalar(alloc),
dupe_behavior,
);
dangling_key = null;
state = try popStack(&stack);
},
else => {
try setStackItemStart(stack, idx);
state = .consuming_map_value;
},
},
.consuming_map_value => switch (char) {
',', '}' => |term| {
const tip = try getStackTip(stack);
try Parser.putMap(
&tip.value.flow_map,
dangling_key.?,
try Value.fromScalar(alloc, contents[tip.item_start..idx]),
dupe_behavior,
);
dangling_key = null;
state = .want_map_key;
if (term == '}') state = try popStack(&stack);
},
else => continue :charloop,
},
.want_map_separator => switch (char) {
' ', '\t' => continue :charloop,
',' => state = .want_map_key,
'}' => state = try popStack(&stack),
else => return error.BadToken,
},
// the root value was closed but there are characters remaining
// in the buffer
.done => return error.BadState,
}
}
// we ran out of characters while still in the middle of an object
if (state != .done) return error.BadState;
return root;
}
inline fn appendListGetValue(list: *Value.List, value: Value) Error!*Value {
@@ -1138,297 +1339,3 @@ pub const Parser = struct {
});
}
};
pub const FlowParser = struct {
const FlowStackItem = struct {
value: *Value,
// lists need this. maps do also for keys and values.
item_start: usize = 0,
};
const FlowStack: type = std.ArrayList(FlowStackItem);
buffer: []const u8,
root: Value,
alloc: std.mem.Allocator,
stack: FlowStack,
state: ParseState,
// make this an ugly state machine parser
const ParseState = enum {
want_list_item,
consuming_list_item,
want_list_separator,
want_map_key,
consuming_map_key,
want_map_value,
consuming_map_value,
want_map_separator,
done,
};
const Error = error{
BadState,
BadToken,
} || std.mem.Allocator.Error;
pub fn initList(alloc: std.mem.Allocator, buffer: []const u8) Error!FlowParser {
return .{
.buffer = buffer,
.root = undefined,
.alloc = alloc,
.stack = undefined,
.state = .want_list_item,
};
}
pub fn initMap(alloc: std.mem.Allocator, buffer: []const u8) Error!FlowParser {
return .{
.buffer = buffer,
.root = undefined,
.alloc = alloc,
.stack = undefined,
.state = .want_map_key,
};
}
pub fn deinit(self: *FlowParser) void {
self.stack.deinit();
}
inline fn getStackTip(stack: FlowStack) Error!*FlowStackItem {
if (stack.items.len == 0) return error.BadState;
return &stack.items[stack.items.len - 1];
}
inline fn setStackItemStart(stack: FlowStack, start: usize) Error!void {
if (stack.items.len == 0) return error.BadState;
stack.items[stack.items.len - 1].item_start = start;
}
inline fn popStack(self: *FlowParser) Parser.Error!ParseState {
if (self.stack.popOrNull() == null)
return error.BadState;
const parent = self.stack.getLastOrNull() orelse return .done;
return switch (parent.value.*) {
.flow_list => .want_list_separator,
.flow_map => .want_map_separator,
else => return error.BadState,
};
}
pub fn parse(self: *FlowParser, dupe_behavior: Parser.DuplicateKeyBehavior) Parser.Error!Value {
// prime the stack:
switch (self.state) {
.want_list_item => {
self.root = Value.newFlowList(self.alloc);
self.stack = try FlowStack.initCapacity(self.alloc, 1);
self.stack.appendAssumeCapacity(.{ .value = &self.root });
},
.want_map_key => {
self.root = Value.newFlowMap(self.alloc);
self.stack = try FlowStack.initCapacity(self.alloc, 1);
self.stack.appendAssumeCapacity(.{ .value = &self.root });
},
else => {
return error.BadState;
},
}
var dangling_key: ?[]const u8 = null;
charloop: for (self.buffer, 0..) |char, idx| {
// std.debug.print("{s} => {c}\n", .{ @tagName(self.state), char });
switch (self.state) {
.want_list_item => switch (char) {
' ', '\t' => continue :charloop,
',' => {
// empty value
const tip = try getStackTip(self.stack);
try tip.value.flow_list.append(Value.newScalar(self.alloc));
tip.item_start = idx + 1;
},
'{' => {
const tip = try getStackTip(self.stack);
const new_map = try Parser.appendListGetValue(
&tip.value.flow_list,
Value.newFlowMap(self.alloc),
);
tip.item_start = idx;
try self.stack.append(.{ .value = new_map });
self.state = .want_map_key;
},
'[' => {
const tip = try getStackTip(self.stack);
const new_list = try Parser.appendListGetValue(
&tip.value.flow_list,
Value.newFlowList(self.alloc),
);
tip.item_start = idx;
try self.stack.append(.{ .value = new_list, .item_start = idx + 1 });
self.state = .want_list_item;
},
']' => {
const finished = self.stack.getLastOrNull() orelse return error.BadState;
if (finished.value.flow_list.items.len > 0 or idx > finished.item_start)
try finished.value.flow_list.append(Value.newScalar(self.alloc));
self.state = try self.popStack();
},
else => {
try setStackItemStart(self.stack, idx);
self.state = .consuming_list_item;
},
},
.consuming_list_item => switch (char) {
',' => {
const tip = try getStackTip(self.stack);
try tip.value.flow_list.append(
try Value.fromScalar(self.alloc, self.buffer[tip.item_start..idx]),
);
tip.item_start = idx + 1;
self.state = .want_list_item;
},
']' => {
const finished = self.stack.getLastOrNull() orelse return error.BadState;
try finished.value.flow_list.append(
try Value.fromScalar(self.alloc, self.buffer[finished.item_start..idx]),
);
self.state = try self.popStack();
},
else => continue :charloop,
},
.want_list_separator => switch (char) {
' ', '\t' => continue :charloop,
',' => {
try setStackItemStart(self.stack, idx);
self.state = .want_list_item;
},
']' => self.state = try self.popStack(),
else => return error.BadToken,
},
.want_map_key => switch (char) {
' ', '\t' => continue :charloop,
// forbid these characters so that flow dictionary keys cannot start
// with characters that regular dictionary keys cannot start with
// (even though they're unambiguous in this specific context).
'{', '[', '#', '>', '|', ',' => return error.BadToken,
':' => {
// we have an empty map key
dangling_key = "";
self.state = .want_map_value;
},
'}' => self.state = try self.popStack(),
else => {
try setStackItemStart(self.stack, idx);
self.state = .consuming_map_key;
},
},
.consuming_map_key => switch (char) {
':' => {
const tip = try getStackTip(self.stack);
dangling_key = try self.alloc.dupe(u8, self.buffer[tip.item_start..idx]);
self.state = .want_map_value;
},
else => continue :charloop,
},
.want_map_value => switch (char) {
' ', '\t' => continue :charloop,
',' => {
const tip = try getStackTip(self.stack);
try Parser.putMap(
&tip.value.flow_map,
dangling_key.?,
Value.newScalar(self.alloc),
dupe_behavior,
);
dangling_key = null;
self.state = .want_map_key;
},
'[' => {
const tip = try getStackTip(self.stack);
const new_list = try Parser.putMapGetValue(
&tip.value.flow_map,
dangling_key.?,
Value.newFlowList(self.alloc),
dupe_behavior,
);
try self.stack.append(.{ .value = new_list, .item_start = idx + 1 });
dangling_key = null;
self.state = .want_list_item;
},
'{' => {
const tip = try getStackTip(self.stack);
const new_map = try Parser.putMapGetValue(
&tip.value.flow_map,
dangling_key.?,
Value.newFlowMap(self.alloc),
dupe_behavior,
);
try self.stack.append(.{ .value = new_map });
dangling_key = null;
self.state = .want_map_key;
},
'}' => {
// the value is an empty string and this map is closed
const tip = try getStackTip(self.stack);
try Parser.putMap(
&tip.value.flow_map,
dangling_key.?,
Value.newScalar(self.alloc),
dupe_behavior,
);
dangling_key = null;
self.state = try self.popStack();
},
else => {
try setStackItemStart(self.stack, idx);
self.state = .consuming_map_value;
},
},
.consuming_map_value => switch (char) {
',', '}' => |term| {
const tip = try getStackTip(self.stack);
try Parser.putMap(
&tip.value.flow_map,
dangling_key.?,
try Value.fromScalar(self.alloc, self.buffer[tip.item_start..idx]),
dupe_behavior,
);
dangling_key = null;
self.state = .want_map_key;
if (term == '}') self.state = try self.popStack();
},
else => continue :charloop,
},
.want_map_separator => switch (char) {
' ', '\t' => continue :charloop,
',' => self.state = .want_map_key,
'}' => self.state = try self.popStack(),
else => return error.BadToken,
},
// the root value was closed but there are characters remaining
// in the buffer
.done => return error.BadState,
}
}
// we ran out of characters while still in the middle of an object
if (self.state != .done) return error.BadState;
return self.root;
}
};