验证XPath表达式

本文介绍了验证XPath表达式的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我想验证用户提供的XPath查询，以确保它在语法上正确.

I would like to validate a user-provided XPath query to ensure that it is syntactically correct.

在没有XML文档的情况下验证" XPath查询是否有意义?

Does it make sense to "validate" an XPath query without an XML document?

我如何在libxml中实现这样的目标?

How can i achieve such a thing in libxml?

推荐答案

您可以使用libxml编译XPath表达式，而无需对其进行评估.请参见 xmlXPathCompile .对于无效的表达式，返回值应为NULL.

You can compile an XPath expression using libxml without evaluating it. See xmlXPathCompile. The return value should be NULL for invalid expressions.

#include <stdio.h> #include <libxml/xpath.h> #include <libxml/xmlerror.h> void handle_structured_error(void *userdata, xmlErrorPtr err) { printf("%s", err->message); } int main(int argc, char **argv) { if (argc < 2) return 1; const char *expr = argv[1]; xmlXPathContextPtr ctx = xmlXPathNewContext(NULL); xmlSetStructuredErrorFunc(ctx, &handle_structured_error); xmlXPathCompExprPtr p = xmlXPathCtxtCompile(ctx, (xmlChar *)expr); if (p) { printf("Valid: %s\n", expr); xmlXPathFreeCompExpr(p); } else { printf("Invalid: %s\n", expr); } xmlXPathFreeContext(ctx); return 0; }