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77 lines
1.4 KiB
77 lines
1.4 KiB
package exql
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import (
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"strings"
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)
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// Columns represents an array of Column.
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type Columns struct {
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Columns []Fragment
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hash hash
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}
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var _ = Fragment(&Columns{})
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// Hash returns a unique identifier.
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func (c *Columns) Hash() string {
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return c.hash.Hash(c)
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}
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// JoinColumns creates and returns an array of Column.
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func JoinColumns(columns ...Fragment) *Columns {
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return &Columns{Columns: columns}
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}
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// OnConditions creates and retuens a new On.
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func OnConditions(conditions ...Fragment) *On {
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return &On{Conditions: conditions}
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}
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// UsingColumns builds a Using from the given columns.
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func UsingColumns(columns ...Fragment) *Using {
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return &Using{Columns: columns}
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}
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// Append
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func (c *Columns) Append(a *Columns) *Columns {
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c.Columns = append(c.Columns, a.Columns...)
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return c
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}
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// IsEmpty
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func (c *Columns) IsEmpty() bool {
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if c == nil || len(c.Columns) < 1 {
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return true
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}
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return false
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}
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// Compile transforms the Columns into an equivalent SQL representation.
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func (c *Columns) Compile(layout *Template) (compiled string, err error) {
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if z, ok := layout.Read(c); ok {
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return z, nil
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}
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l := len(c.Columns)
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if l > 0 {
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out := make([]string, l)
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for i := 0; i < l; i++ {
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out[i], err = c.Columns[i].Compile(layout)
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if err != nil {
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return "", err
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}
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}
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compiled = strings.Join(out, layout.IdentifierSeparator)
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} else {
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compiled = "*"
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}
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layout.Write(c, compiled)
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return
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}
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