package compiler

import "fmt"

type SyntaxError struct {
	Message string
}

func newSyntaxError(msg string) *SyntaxError {
	return &SyntaxError{
		Message: msg,
	}
}

func (e *SyntaxError) Error() string {
	return fmt.Sprintf("syntax error: %s", e.Message)
}

var (
	// lexical errors
	synErrIncompletedEscSeq     = newSyntaxError("incompleted escape sequence; unexpected EOF following \\")
	synErrInvalidEscSeq         = newSyntaxError("invalid escape sequence")
	synErrInvalidCodePoint      = newSyntaxError("code points must consist of just 4 or 6 hex digits")
	synErrCharPropInvalidSymbol = newSyntaxError("invalid character property symbol")
	SynErrFragmentInvalidSymbol = newSyntaxError("invalid fragment symbol")

	// syntax errors
	synErrUnexpectedToken        = newSyntaxError("unexpected token")
	synErrNullPattern            = newSyntaxError("a pattern must be a non-empty byte sequence")
	synErrAltLackOfOperand       = newSyntaxError("an alternation expression must have operands")
	synErrRepNoTarget            = newSyntaxError("a repeat expression must have an operand")
	synErrGroupNoElem            = newSyntaxError("a grouping expression must include at least one character")
	synErrGroupUnclosed          = newSyntaxError("unclosed grouping expression")
	synErrGroupNoInitiator       = newSyntaxError(") needs preceding (")
	synErrGroupInvalidForm       = newSyntaxError("invalid grouping expression")
	synErrBExpNoElem             = newSyntaxError("a bracket expression must include at least one character")
	synErrBExpUnclosed           = newSyntaxError("unclosed bracket expression")
	synErrBExpInvalidForm        = newSyntaxError("invalid bracket expression")
	synErrRangeInvalidOrder      = newSyntaxError("a range expression with invalid order")
	synErrCPExpInvalidForm       = newSyntaxError("invalid code point expression")
	synErrCPExpOutOfRange        = newSyntaxError("a code point must be between U+0000 to U+10FFFF")
	synErrCharPropExpInvalidForm = newSyntaxError("invalid character property expression")
	synErrCharPropUnsupported    = newSyntaxError("unsupported character property")
	synErrFragmentExpInvalidForm = newSyntaxError("invalid fragment expression")
)