X-Git-Url: https://git.mxchange.org/?a=blobdiff_plain;f=utils%2Fxmlgrep%2FREADME;h=33294ffbd19c639ade5cfd71396839fe802c2e64;hb=a89a28c4e62a63e05b6b889274fa848ea2bda007;hp=29be06bb32e79ea88982c47c95a65f997b38e501;hpb=64a07de08039a5316105656ec73faf63df8ed4ab;p=flightgear.git

diff --git a/utils/xmlgrep/README b/utils/xmlgrep/README
index 29be06bb3..33294ffbd 100644
--- a/utils/xmlgrep/README
+++ b/utils/xmlgrep/README
@@ -1,62 +1,146 @@
+This library is specially designed for reading xml configuration files and
+to be as low on memory management as possible. Modifying or writing xml files
+is not planned for the future. In most situations being able to gather data
+by reading an xml file is more than enough and the read-only decision
+provides a number of advantages over a one-size fits all approach. For isntance
+the memory footprint can be kept low and the library can be kept simple.
+
+To achieve these goals the mmap function is used to map the configuration file
+to a memory region. The only places where memory is allocated is when creating
+a new XML-id, when requesting a string from a node, when requestiong the node
+name or when a request is made to copy a node into a new memory region.
+
+Using this library should be pretty simple for most tasks; just open a file,
+read every parameter one by one and close the id again.
+{
+   void *xid;
+
+   xid = xmlOpen("/tmp/file.xml");
+   xpos = xmlNodeGetDouble(xid, "/configuration/x-pos");
+   ypos = xmlNodeGetDouble(xid, "/configuration/y-pos");
+   zpos = xmlNodeGetDouble(xid, "/configuration/z-pos");
+   xmlClose(xid);
+}
+
+While it is certainly possible to access every node directly by calling the
+xmlNodeGet(Int/Double/String) functions, when more than one node need to be
+gathered from a parent node it is advised to get the id of the parent node
+and work from there since the XML-id holds the boundaries of the (parent)node
+which limits the searching area resulting in improved searching speed.
+{
+   void *xnid;
+   char *s;
+
+   xnid = xmlNodeGet(id, "/configuration/setup/");
+   version = xmlNodeGetDouble(xnid, "version");
+   s = xmlNodeGetString(xnid, "author");
+   if (s) author = s;
+   free(s);
+   free(xnid);
+}
+
+Overview of the available functions:
+ ----------------------------------------------------------------------------- 
 #
 # Functions to Open and Close the XML file
 # e.g.
 #   id = xmlOpen("/tmp/file.xml");
 #   xmlClose(id);
 #
-void *xmlOpen(const char *);
-void xmlClose(const void *);
+void *xmlOpen(const char *filename);
+void *xmlInitBuffer(const char *buffer, size_t size);
+void xmlClose(void *xid);
 
 #
 # Get the Id of a node at the specified path
 # e.g.
-#    xnid = xmlGetNode(id, "/path/to/specified/node");
+#    xnid = xmlNodeGet(id, "/path/to/specified/node");
 #
-void *xmlGetNode(const void *, const char *);
-void *xmlCopyNode(void *, const char *);
+void *xmlNodeGet(const void *xid, const char *path);
+void *xmlNodeCopy(const void *xid, const char *path);
 
 #
-# Functions to walk the node tree an process them one by one.
+# Functions to walk the node tree and process them one by one.
 # e.g.
 #   xmid = xmlMarkId(id);
-#   num = xmlGetNumElements(xmid);
+#   num = xmlNodeGetNum(xmid, "node");
 #   for (i=0; i<num; i++) {
-#      if (xmlGetNextElement(id, xmid, "element") != 0) {
+#      if (xmlNodeGetPos(id, xmid, "element", i) != 0) {
 #         if ((s = xmlGetString(xmid)) != 0) {
 #            printf("%s\n", s);
 #            free(s);
 #         }
 #      }
 #   }
+#   free(xmid);
 #
-void *xmlMarkId(void *);
-unsigned int xmlGetNumElements(void *, const char *);
-void *xmlGetNextElement(const void *, void *, const char *);
+void *xmlMarkId(const void *xid);
+unsigned int xmlNodeGetNum(const void *xid, const char *path);
+void *xmlNodeGetPos(const void *pid, void *xid, const char *element, int pos);
+
+#
+# Get the name of the current node
+#
+char *xmlNodeGetName(const void *xid);
+size_t xmlNodeCopyName(const void *xid, const char *buffer, size_t size);
 
 #
 # These functions work on the current node.
 # e.g.
-#    xnid = xmlGetNode(id, "/path/to/last/node");
+#    xnid = xmlNodeGet(id, "/path/to/last/node");
 #    i = xmlGetInt(xnid);
 # or
-#    xnid = xmlGetNode(id, "/path/to/specified/node");
+#    xnid = xmlNodeGet(id, "/path/to/specified/node");
 #    if (xmlCompareString(xnid, "value") == 0) printf("We have a match!\n");
 #
-long int xmlGetInt(void *);
-double xmlGetDouble(void *);
-char *xmlGetString(void *);
-int xmlCompareString(const void *, const char *);
+long int xmlGetInt(const void *xid);
+double xmlGetDouble(const void *xid);
+char *xmlGetString(const void *xid);
+size_t xmlCopyString(const void *xid, char *buffer, const size_t size);
+int xmlCompareString(const void *xid, const char *str);
 
 #
 # These functions work on a specified node path
 # e.g.
-#    d = xmlGetNodeDouble(id, "/path/to/node");
+#    d = xmlNodeGetDouble(id, "/path/to/node");
+# or
+#    xnid = xmlNodeGet(id, "/path/to");
+#    i = xmlNodeGetInt(xnid, "node");
+#
+long int xmlNodeGetInt(const void *xid, const char *path);
+double xmlNodeGetDouble(const void *xid, const char *path);
+char *xmlNodeGetString(const void *xid, const char *path);
+size_t xmlNodeCopyString(const void *xid, const char *path,
+                            char *buffer, const size_t size);
+int xmlNodeCompareString(const void *xid, const char *path, const char *str);
+
+#
+# These functions work on a specified atribute
+# e.g.
+#    i = xmlAttributeGetInt(id, "n");
+#
 # or
-#    xnid = xmlGetNode(id, "/path/to");
-#    i = xmlGetNodeInt(xnid, "node");
-#
-long int xmlGetNodeInt(void *, const char *);
-double xmlGetNodeDouble(void *, const char *);
-char *xmlGetNodeString(void *, const char *);
-unsigned xmlCopyNodeString(void *, const char *, char *, const unsigned int);
-int xmlCompareNodeString(const void *, const char *, const char *);
+#    s = xmlAttributeGetString(id, "type");
+#    if (s) printf("node is of type '%s'\n", s);
+#    free(s);
+#
+long int xmlAttributeGetInt(const void *xid, const char *attr);
+double xmlAttributeGetDouble(const void *xid, const char *attr);
+char *xmlAttributeGetString(const void *xid, const char *attr);
+size_t xmlAttributeCopyString(const void *xid, const char *attr,
+                                 const char *buffer, size_t size);
+int xmlAttributeCompareString(const void *xid, const char *attr,
+                                 const char *str);
+
+#
+# Error detection and reporting functions
+#
+# char *err_str = xmlErrorGetString(id, 0);
+# size_t err_lineno = xmlErrorGetLineNo(id, 0);
+# int err = xmlErrorGetNo(id, 1); /* clear last error */
+# if (err) printf("Error #%i at line %u: '%s'\n", err, err_lineno, err_str);
+#
+int xmlErrorGetNo(const void *xid, int clear);
+size_t xmlErrorGetLineNo(const void *xid, int clear);
+size_t xmlErrorGetColumnNo(const void *xid, int clear);
+const char *xmlErrorGetString(const void *xid, int clear);