mirror of
https://github.com/neilotoole/sq.git
synced 2024-12-19 22:21:56 +03:00
111 lines
2.7 KiB
Go
111 lines
2.7 KiB
Go
package render
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import (
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"strings"
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"github.com/neilotoole/sq/libsq/ast"
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"github.com/neilotoole/sq/libsq/core/errz"
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"github.com/neilotoole/sq/libsq/core/stringz"
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)
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func doFunction(rc *Context, fn *ast.FuncNode) (string, error) {
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sb := strings.Builder{}
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fnName := strings.ToLower(fn.FuncName())
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if f, ok := rc.Renderer.FunctionOverrides[fnName]; ok {
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// The SQL function name has a custom renderer.
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return f(rc, fn)
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}
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if f, ok := rc.Renderer.FunctionNames[fnName]; ok {
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// The SLQ function name is mapped to a different SQL function
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// for this dialect.
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fnName = f
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}
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children := fn.Children()
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if len(children) == 0 {
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sb.WriteString(fnName)
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sb.WriteRune('(')
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if fnName == "count" {
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// Special handling for the count function, because COUNT()
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// isn't valid, but COUNT(*) is.
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sb.WriteRune('*')
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}
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sb.WriteRune(')')
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return sb.String(), nil
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}
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// Special handling for "count_unique(.col)" function. We translate
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// it to "SELECT count(DISTINCT col)".
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if fnName == "count_unique" {
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sb.WriteString("count(DISTINCT ")
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} else {
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sb.WriteString(fnName)
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sb.WriteRune('(')
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}
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for i, child := range children {
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if i > 0 {
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sb.WriteString(", ")
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}
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switch node := child.(type) {
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case *ast.ColSelectorNode, *ast.TblColSelectorNode, *ast.TblSelectorNode:
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s, err := renderSelectorNode(rc.Dialect, node)
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if err != nil {
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return "", err
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}
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sb.WriteString(s)
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case *ast.OperatorNode:
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sb.WriteString(node.Text())
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case *ast.LiteralNode:
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// TODO: This is all a bit of a mess. We probably need to
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// move to using bound parameters instead of inlining
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// literal values.
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val, wasQuoted, err := unquoteLiteral(node.Text())
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if err != nil {
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return "", err
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}
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if wasQuoted {
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// The literal had quotes, so it's a regular string.
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sb.WriteString(stringz.SingleQuote(val))
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} else {
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sb.WriteString(val)
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}
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case *ast.ExprNode:
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s, err := rc.Renderer.Expr(rc, node)
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if err != nil {
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return "", err
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}
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sb.WriteString(s)
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default:
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return "", errz.Errorf("unknown AST child node %T: %s", node, node)
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}
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}
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sb.WriteRune(')')
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sql := sb.String()
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return sql, nil
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}
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// doFuncRowNum renders the rownum() function.
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func doFuncRowNum(rc *Context, fn *ast.FuncNode) (string, error) {
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a, _ := ast.NodeRoot(fn).(*ast.AST)
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obNode := ast.FindFirstNode[*ast.OrderByNode](a)
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if obNode != nil {
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obClause, err := rc.Renderer.OrderBy(rc, obNode)
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if err != nil {
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return "", err
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}
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return "(row_number() OVER (" + obClause + "))", nil
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}
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// It's not entirely clear that this "ORDER BY 1" mechanism
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// is the correct approach, but it seems to work for SQLite and Postgres.
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return "(row_number() OVER (ORDER BY 1))", nil
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}
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