package core:encoding/xml

Source

Attribute :: struct {
	key: string,
	val: string,
}

Attributes :: [dynamic]Attribute

Document :: struct {
	elements:        [dynamic]Element,
	element_count:   u32,
	prologue:        [dynamic]Attribute,
	encoding:        Encoding,
	doctype:         struct {
		// 			We only scan the 
		ident: string,
		rest:  string,
	},
	// 		If we encounter comments before the root node, and the option to intern comments is given, this is where they'll live.
	// 		Otherwise they'll be in the element tree.
	comments:        [dynamic]string,
	// 		Internal
	tokenizer:       ^Tokenizer,
	allocator:       runtime.Allocator,
	// 		Input. Either the original buffer, or a copy if `.Input_May_Be_Modified` isn't specified.
	input:           []u8,
	strings_to_free: [dynamic]string,
}

Element :: struct {
	ident:    string,
	value:    string,
	attribs:  [dynamic]Attribute,
	kind:     enum int {
		Element = 0, 
		Comment, 
	},
	parent:   u32,
	children: [dynamic]u32,
}

Element_ID :: u32

Encoding :: enum int {
	Unknown, 
	UTF_8, 
	ISO_8859_1, 
	// 		Aliases
	LATIN_1    = 2, 
}

Error :: enum int {
	// 		General return values.
	None                          = 0, 
	General_Error, 
	Unexpected_Token, 
	Invalid_Token, 
	// 		Couldn't find, open or read file.
	File_Error, 
	// 		File too short.
	Premature_EOF, 
	// 		XML-specific errors.
	No_Prolog, 
	Invalid_Prolog, 
	Too_Many_Prologs, 
	No_DocType, 
	Too_Many_DocTypes, 
	DocType_Must_Preceed_Elements, 
	// 		If a DOCTYPE is present _or_ the caller
	// 		asked for a specific DOCTYPE and the DOCTYPE
	// 		and root tag don't match, we return `.Invalid_DocType`.
	Invalid_DocType, 
	Invalid_Tag_Value, 
	Mismatched_Closing_Tag, 
	Unclosed_Comment, 
	Comment_Before_Root_Element, 
	Invalid_Sequence_In_Comment, 
	Unsupported_Version, 
	Unsupported_Encoding, 
	// 		
	Unhandled_Bang, 
	Duplicate_Attribute, 
	Conflicting_Options, 
}

Error_Handler :: proc(pos: Pos, fmt: string, args: ..any)

Option_Flag :: enum int {
	// 		If the caller says that input may be modified, we can perform in-situ parsing.
	// 		If this flag isn't provided, the XML parser first duplicates the input so that it can.
	Input_May_Be_Modified, 
	// 		Document MUST start with `
	Must_Have_Prolog, 
	// 		Document MUST have a `
	Must_Have_DocType, 
	// 		By default we skip comments. Use this option to intern a comment on a parented Element.
	Intern_Comments, 
	// 		How to handle unsupported parts of the specification, like 
	Error_on_Unsupported, 
	Ignore_Unsupported, 
	// 		By default CDATA tags are passed-through as-is.
	// 		This option unwraps them when encountered.
	Unbox_CDATA, 
	// 		By default SGML entities like `>`, ` ` and ` ` are passed-through as-is.
	// 		This option decodes them when encountered.
	Decode_SGML_Entities, 
	// 		If a tag body has a comment, it will be stripped unless this option is given.
	Keep_Tag_Body_Comments, 
}

Option_Flags :: bit_set[Option_Flag; u16]

Options :: struct {
	flags:            bit_set[Option_Flag; u16],
	expected_doctype: string,
}

Pos :: struct {
	file:   string,
	offset: int,
	// starting at 0
	line:   int,
	// starting at 1
	column: int,
}

Token :: struct {
	kind: Token_Kind,
	text: string,
	pos:  Pos,
}

Token_Kind :: enum int {
	Invalid, 
	Ident, 
	Literal, 
	Rune, 
	String, 
	Double_Quote,  // "
	Single_Quote,  // '
	Colon,         // :
	Eq,            // =
	Lt,            // <
	Gt,            // >
	Exclaim,       // !
	Question,      // ?
	Hash,          // #
	Slash,         // /
	Dash,          // -
	Open_Bracket,  // [
	Close_Bracket, // ]
	EOF, 
}

Tokenizer :: struct {
	// Immutable data
	path:        string,
	src:         string,
	err:         Error_Handler,
	// Tokenizing state
	ch:          rune,
	offset:      int,
	read_offset: int,
	line_offset: int,
	line_count:  int,
	// Mutable data
	error_count: int,
}

CDATA_END :: "]]>"

CDATA_START :: "

COMMENT_END :: "-->"

COMMENT_START :: ", preceded by a character that's not a dash.

"For compatibility, the string "--" (double-hyphen) must not occur within comments."

See: https://www.w3.org/TR/2006/REC-xml11-20060816/#dt-comment

Thanks to the length (4) of the comment start, we also have enough lookback,
and the peek at the next byte asserts that there's at least one more character
that's a `>`.