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implement writexml() function for writing non-standard XML files

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(that is: such that don't use PropertyList as root element and have
data hidden in attributes)
This commit is contained in:
mfranz 2007-07-01 15:05:16 +00:00
parent d1adc37872
commit faf9ea862d
1 changed files with 56 additions and 12 deletions
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68
Nasal/io.nas
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@ -26,25 +26,30 @@ var ifmts = {dir:4, reg:8, lnk:10, sock:12, fifo:1, blk:6, chr:2};
foreach(fmt; keys(ifmts))
caller(0)[0]["is" ~ fmt] = _gen_ifmt_test(ifmts[fmt]);
# The following two functions are for reading generic XML files into
# the property tree and for writing them from there to the disk. The
# built-in fgcommands (load, save, loadxml, savexml) are for FlightGear's
# own <PropertyList> XML files only, as they only handle a limited
# number of very specific attributes. The io.readxml() loader turns
# attributes into regular children with a configurable prefix prepended
# to their name, while io.writexml() turns such nodes back into
# attributes. The two functions have their own limitations, but can
# easily get extended to whichever needs. The underlying parsexml()
# command will handle any XML file.
# Reads an XML file from an absolute path and returns it as property
# tree. All nodes are of type STRING. Data are only written to leafs.
# Attributes are written as regular nodes with the optional prefix
# prepended to the name. If the prefix is nil, then attributes are
# ignored. Returns nil on error.
# tree. All nodes will be of type STRING. Data are only written to
# leafs. Attributes are written as regular nodes with the optional
# prefix prepended to the name. If the prefix is nil, then attributes
# are ignored. Returns nil on error.
#
# NOTE: this function is meant for importing 'foreign' XML files, *not*
# for reading FlighGear's standard "PropertyList" XML files. For those
# we have better means, like the loadxml/savexml fgcommands. This
# function does neither interpret the "type" nor the "n" (index) or
# "archive" attribute.
#
var readxml = func(file, prefix = "") {
var readxml = func(file, prefix = "___") {
var stack = [[{}, ""]];
var node = props.Node.new();
var tree = node; # prevent GC
var start = func(name, attr) {
var index = stack[-1][0];
if (!contains(index, name))
if(!contains(index, name))
index[name] = 0;
node = node.getChild(name, index[name], 1);
@ -67,4 +72,43 @@ var readxml = func(file, prefix = "") {
return parsexml(file, start, end, data) == nil ? nil : tree;
}
# Writes a property tree as returned by readxml() to a file. Chidren
# with name starting with <prefix> are again turned into attributes of
# their parent. <node> must contain exactly one child, which will
# become the XML file's outmost element.
#
var writexml = func(file, node, indent = "\t", prefix = "___") {
var root = node.getChildren();
if(!size(root)) die("writexml(): tree doesn't have a root node");
if(substr(file, -4) != ".xml") file ~= ".xml";
var fh = open(file, "w");
var pre = size(prefix);
write(fh, "<?xml version=\"1.0\"?>\n\n");
var writenode = func(n, ind = "") {
var name = n.getName();
var name_attr = name;
var children = [];
foreach(var c; n.getChildren()) {
var aname = c.getName();
if(substr(aname, 0, pre) == prefix)
name_attr ~= " " ~ substr(aname, pre) ~ '="' ~ c.getValue() ~ '"';
else
append(children, c);
}
if(size(children)) {
write(fh, ind ~ "<" ~ name_attr ~ ">\n");
foreach(var c; children)
writenode(c, ind ~ indent);
write(fh, ind ~ "</" ~ name ~ ">\n");
} elsif((var value = n.getValue()) != nil) {
write(fh, ind ~ "<" ~ name_attr ~ ">" ~ value ~ "</" ~ name ~ ">\n");
} else {
write(fh, ind ~ "<" ~ name_attr ~ "/>\n");
}
}
writenode(root[0]);
close(fh);
if(size(root) != 1) die("writexml(): tree has more than one root node");
}