Import source code of lexer generator

From: https://github.com/nihei9/maleeni

1 files changed, 45 insertions, 0 deletions

diff --git a/spec/grammar/parser/syntax_error.go b/spec/grammar/parser/syntax_error.go
new file mode 100644
index 0000000..719fb94
--- /dev/null
+++ b/spec/grammar/parser/syntax_error.go
@@ -0,0 +1,45 @@
+package parser
+
+type SyntaxError struct {
+	message string
+}
+
+func newSyntaxError(message string) *SyntaxError {
+	return &SyntaxError{
+		message: message,
+	}
+}
+
+func (e *SyntaxError) Error() string {
+	return e.message
+}
+
+var (
+	// lexical errors
+	synErrIDInvalidChar            = newSyntaxError("an identifier can contain only the lower-case letter, the digits, and the underscore")
+	synErrIDInvalidUnderscorePos   = newSyntaxError("the underscore cannot be placed at the beginning or end of an identifier")
+	synErrIDConsecutiveUnderscores = newSyntaxError("the underscore cannot be placed consecutively")
+	synErrIDInvalidDigitsPos       = newSyntaxError("the digits cannot be placed at the biginning of an identifier")
+	synErrUnclosedTerminal         = newSyntaxError("unclosed terminal")
+	synErrUnclosedString           = newSyntaxError("unclosed string")
+	synErrIncompletedEscSeq        = newSyntaxError("incompleted escape sequence; unexpected EOF following a backslash")
+	synErrEmptyPattern             = newSyntaxError("a pattern must include at least one character")
+	synErrEmptyString              = newSyntaxError("a string must include at least one character")
+
+	// syntax errors
+	synErrInvalidToken           = newSyntaxError("invalid token")
+	synErrTopLevelDirNoSemicolon = newSyntaxError("a top-level directive must be followed by ;")
+	synErrNoProductionName       = newSyntaxError("a production name is missing")
+	synErrNoColon                = newSyntaxError("the colon must precede alternatives")
+	synErrNoSemicolon            = newSyntaxError("the semicolon is missing at the last of an alternative")
+	synErrLabelWithNoSymbol      = newSyntaxError("a label must follow a symbol")
+	synErrNoLabel                = newSyntaxError("an identifier that represents a label is missing after the label marker @")
+	synErrNoDirectiveName        = newSyntaxError("a directive needs a name")
+	synErrNoOrderedSymbolName    = newSyntaxError("an ordered symbol name is missing")
+	synErrUnclosedDirGroup       = newSyntaxError("a directive group must be closed by )")
+	synErrPatternInAlt           = newSyntaxError("a pattern literal cannot appear directly in an alternative. instead, please define a terminal symbol with the pattern literal")
+	synErrStrayExpOp             = newSyntaxError("an expansion operator ... must be preceded by an identifier")
+	synErrInvalidExpOperand      = newSyntaxError("an expansion operator ... can be applied to only an identifier")
+	synErrSemicolonNoNewline     = newSyntaxError("a semicolon must be followed by a newline")
+	synErrFragmentNoPattern      = newSyntaxError("a fragment needs one pattern element")
+)