Add a CIF parser

io/pdbx/cif/doc.go

@@ -0,0 +1,7 @@
+/*
+Package cif provides utilities to read and write CIF v1.1 files.
+
+See https://www.iucr.org/resources/cif/spec/version1.1 for a full
+description of the CIF v1.1 syntax.
+*/
+package cif

io/pdbx/cif/errors.go

@@ -0,0 +1,22 @@
+package cif
+
+import "fmt"
+
+// A CIFSyntaxError is a syntax error produced while parsing a CIF file.
+type CIFSyntaxError struct {
+	Line int
+	Msg  string
+}
+
+// Wrap creates a new CIFSyntaxError wrapped with msg.
+func (s CIFSyntaxError) Wrap(format string, a ...any) error {
+	return CIFSyntaxError{
+		Line: s.Line,
+		Msg:  fmt.Sprintf("%s: %s", fmt.Sprintf(format, a...), s.Msg),
+	}
+}
+
+// Error returns the formatted error message.
+func (s CIFSyntaxError) Error() string {
+	return fmt.Sprintf("CIF syntax error at line %v: %s", s.Line, s.Msg)
+}