public RepeatClause(AbstractClause _clause, int minnum, int maxnum)
{
clause = _clause;
minNum = minnum;
maxNum = maxnum;
}
/// <summary>
/// 这里不考虑COMPUTE与UNION运算，使用COMPUTE的场合不应使用本类，如果实际需要使用UNION，需要写成视图，
/// 再写视图查询，或者如在MS SQL SERVER中使用内联视图。
/// 我们只关心SELECT语句的第一层的构成，并且我们假定SQL语句语法是正确的，因些可以忽略许多
/// 细节的语法，语法构造的EBNF如下：（T表示终截符）
/// EXP::=[T*][(( '(' SELECT | (EXP ( , EXP )*) ')' ) | T)* ]
/// EXPLIST::=EXP ( , EXP )*
/// SELECT::=select EXPLIST from EXPLIST [where EXP][group by EXPLIST [having EXP]][order by EXPLIST]
/// 因为我们不希望实面全SQL语法的分析，别名关键字AS在语法中成为上下文相关的，这样我们不在语法中定义它，
/// 而在语法分析完成后，对语法片断采用正则表达式或字符串处理进一点分析。
/// </summary>
/// <param name="sqlstr"></param>
public SQLSelectParser(string sqlstr)
{
context = new SQLParserContext(sqlstr);
AndClause selectQuery = AbstractClause.NewAnd;
OrClause exp = AbstractClause.NewOr;
exp.Build(AbstractClause.Terminal.Repeat(),
AbstractClause.Identic.And("(",
selectQuery.Alternative(exp.And(AbstractClause.Identic.And(",", exp).Repeat())),
")")[SQLParserClauseType.PARENTHESES].Alternative(AbstractClause.Terminal).Repeat()
); //表达式语法定义
AbstractClause expression = exp[SQLParserClauseType.EXPRESSION];
AbstractClause expList = expression.And(AbstractClause.Identic.And(",", expression).Repeat()); //表达式列表语法定义
selectQuery.Build("select",
expList[SQLParserClauseType.SELECT][SQLParserClauseType.COUNT],
AbstractClause.Identic.And("from", expList)[SQLParserClauseType.FROM][SQLParserClauseType.COUNT][SQLParserClauseType.COUNT],
AbstractClause.Nilpotent.Or(
AbstractClause.Identic.And("where", expression[SQLParserClauseType.WHERE]),
AbstractClause.Identic.And("group by", expList[SQLParserClauseType.GROUPBYLIST].Or("having", expression[SQLParserClauseType.HAVING])
),
AbstractClause.Identic.And("order by", expList[SQLParserClauseType.ORDERBYLIST])
)[SQLParserClauseType.COUNT][SQLParserClauseType.COUNT][SQLParserClauseType.COUNT]
); //SELECT语句语法定义
selectQuery.Parse(context);
//表别名处理
Parentheses.Sort(new StringLengthComparer());
noParenthesesFrom = context.FromClause;
int pi = 0;
foreach (string s in Parentheses)
{
noParenthesesFrom = noParenthesesFrom.Replace(s, "__EXP" + pi + "__");
pi++;
}
string regex = @"
(?:
from\s+(\w+(?:\s+(?!left)(?!rigth)(?!full)(?!inner)(?!outer)(?!join)\w+)?)\s*
(?:
(?:
(?:
(?:
left|right|full|inner|outer|join
)
\s+
)+
(\w+(?:\s+(?!on)\w+)?)
\s+on\s+(?:(?!left)(?!rigth)(?!full)(?!inner)(?!outer)(?!join)[^\s]+\s*)+
)+
|
(?:,\s*(\w+(?:\s+\w+)?)\s*)+
)?
)";
System.Text.RegularExpressions.RegexOptions options = ((System.Text.RegularExpressions.RegexOptions.IgnorePatternWhitespace | System.Text.RegularExpressions.RegexOptions.Multiline)
| System.Text.RegularExpressions.RegexOptions.IgnoreCase);
System.Text.RegularExpressions.Regex reg = new System.Text.RegularExpressions.Regex(regex, options);
string regex0 = "(\\w+)(?:\\s+(\\w+))?";
System.Text.RegularExpressions.Regex reg0 = new System.Text.RegularExpressions.Regex(regex0, options);
Match m = reg.Match(noParenthesesFrom);
if (m.Success)
{
for (int i = 1; i <= 3; i++)
{
Group g = m.Groups[i];
foreach (Capture c in g.Captures)
{
Match m0 = reg0.Match(c.Value);
if (m0.Success)
{
if (m0.Groups[2].Captures.Count > 0)
{
tableAlias[m0.Groups[1].Value] = m0.Groups[2].Value;
}
else
{
tableAlias[m0.Groups[1].Value] = m0.Groups[1].Value;
}
}
}
}
}
//select 列表处理
for (int i = 0; i < Expressions.Count; i++)
{
string field = Expressions[i] as string;
//消除[all | distinct][top n [percent] [with ties]]
Regex regexp = new Regex("^(?:all|distinct)?\\s*(?:top\\s+[0-9]{0,3}\\s*(?:percent)?\\s*(?:with\\s+ties)?)?", options);
Match match = regexp.Match(field.ToLower());
if (match.Success)
{
field = field.Substring(match.Index + match.Length);
Expressions[i] = field;
}
break;
}
//处理SELECT列表，构造字段原始名与别名的对应关系，SQL语句中的*号无法在语法分析时扩展成各个列名
string regex1 = "(.*)(?:\\s+as\\s+(\\w+))?\\s* ";
System.Text.RegularExpressions.RegexOptions options1 = (((System.Text.RegularExpressions.RegexOptions.RightToLeft | System.Text.RegularExpressions.RegexOptions.IgnorePatternWhitespace)
| System.Text.RegularExpressions.RegexOptions.Multiline)
| System.Text.RegularExpressions.RegexOptions.IgnoreCase);
System.Text.RegularExpressions.Regex reg1 = new System.Text.RegularExpressions.Regex(regex1, options1);
string regex2 = "(\\w+)\\.(\\w+)";
System.Text.RegularExpressions.RegexOptions options2 = (((System.Text.RegularExpressions.RegexOptions.RightToLeft | System.Text.RegularExpressions.RegexOptions.IgnorePatternWhitespace)
| System.Text.RegularExpressions.RegexOptions.Multiline)
| System.Text.RegularExpressions.RegexOptions.IgnoreCase);
System.Text.RegularExpressions.Regex reg2 = new System.Text.RegularExpressions.Regex(regex2, options2);
for (int i = 0; i < Expressions.Count; i++)
{
string field = Expressions[i] as string;
Match match = reg1.Match(field);
if (match.Success)
{
if (match.Groups[2].Captures.Count > 0)
{
fieldAlias[match.Groups[1].Value] = match.Groups[2].Value;
fieldNames[match.Groups[2].Value] = match.Groups[1].Value;
}
else
{
string alias = match.Groups[1].Value;
Match mm = reg2.Match(alias);
if (mm.Success)
{
alias = mm.Groups[2].Value;
}
fieldAlias[match.Groups[1].Value] = alias;
fieldNames[alias] = match.Groups[1].Value;
}
}
}
}
public ArgumentClause(AbstractClause _clause, object arg)
{
clause = _clause;
clauseArg = arg;
}
