+def revert_mhchem(document):
+ "Revert mhchem loading to preamble code"
+ i = 0
+ j = 0
+ k = 0
+ i = find_token(document.header, "\\use_mhchem 1", 0)
+ if i != -1:
+ mhchem = "auto"
+ else:
+ i = find_token(document.header, "\\use_mhchem 2", 0)
+ if i != -1:
+ mhchem = "on"
+ if mhchem == "auto":
+ j = find_token(document.body, "\\cf{", 0)
+ if j != -1:
+ mhchem = "on"
+ else:
+ j = find_token(document.body, "\\ce{", 0)
+ if j != -1:
+ mhchem = "on"
+ if mhchem == "on":
+ add_to_preamble(document, ["% this command was inserted by lyx2lyx"])
+ add_to_preamble(document, ["\\PassOptionsToPackage{version=3}{mhchem}"])
+ add_to_preamble(document, ["\\usepackage{mhchem}"])
+ k = find_token(document.header, "\\use_mhchem", 0)
+ if k == -1:
+ document.warning("Malformed LyX document: Could not find mhchem setting.")
+ return
+ del document.header[k]
+
+