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# sql.tcl -- SQL code generator
# Copyright 2002-2004 The Apache Software Foundation
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# This class provides a way to abstract to some extent the
# SQL code generation. It's supposed to provide a bridge to
# different implementation in various backends for specific
# functionalities
#
# $Id: sql.tcl 1596885 2014-05-22 14:19:10Z mxmanghi $
package require Itcl
###
catch { ::itcl::delete class ::DIO::Sql }
###
namespace eval ::Aida {
proc generator {backend} {
}
::itcl::class Sql {
public variable backend
public variable what
public variable table
constructor { backend } {
}
private method where_clause {where_arguments}
public method build_select_query {table row_d}
public method quote {field_value}
protected method field_value {table_name field_name val} {
return "'[quote $val]'"
}
public method build_insert_query {table row_d}
public method build_update_query {table row_d}
}
# -- build_insert_query
#
#
::itcl::body Sql::build_insert_query {table row_d} {
set vars [dict keys $row_d]
foreach field $vars {
lappend vals [$this field_value $table $field [dict get $row_d $field]]
}
return "INSERT INTO $table ([join $vars {,}]) VALUES ([join $vals {,}])"
}
# -- build_update_query
#
#
::itcl::body Sql::build_update_query {table row_d} {
foreach field [dict keys $row_d] {
lappend rowfields "$field=[field_value $table $field [dict get $row_d $field]]"
}
return "UPDATE $table SET [join $rowfields {,}]"
}
# build_where_clause
#
#
::itcl::body Sql::where_clause {where_expr} {
set sql ""
for {set i 0} {$i < [llength [dict keys $where_expr]]} {incr i} {
set d [dict get $where_expr $i]
set col [dict get $d column]
set op [dict get $d operator]
if {$i > 0} {
append sql " [dict get $d logical]"
}
switch $op {
"eq" {
set sqlop "="
}
"ne" {
set sqlop "!="
}
"lt" {
set sqlop "<"
}
"gt" {
set sqlop ">"
}
"le" {
set sqlop "<="
}
"ge" {
set sqlop ">="
}
"notnull" {
append sql " $col IS NOT NULL"
continue
}
"null" {
append sql " $col IS NULL"
continue
}
}
set predicate [dict get $d predicate]
if {[::string first {%} $predicate] != -1} {
append sql " $col LIKE [$this field_value $table $col [[string range $predicate 1 end]]"
} else {
append sql " $col$sqlop[$this field_value $table $col $predicate]"
}
}
return $sql
}
#
# quote - given a string, return the same string with any single
# quote characters preceded by a backslash
#
::itcl::body Sql::quote {field_value} {
regsub -all {'} $field_value {\'} field_value
return $field_value
}
# build_select_query - build a select query based on given arguments,
# which can include a table name, a select statement, switches to
# turn on boolean AND or OR processing, and possibly
# some key-value pairs that cause the where clause to be
# generated accordingly
::itcl::body Sql::build_select_query {args} {
set bool AND
set first 1
set req ""
set table $from_table
set what "*"
set parser_st state0
set condition_count 0
set where_expr [dict create]
# for each argument passed us...
# (we go by integers because we mess with the index depending on
# what we find)
#puts "args: $args"
for {set i 0} {$i < [llength $args]} {incr i} {
# fetch the argument we're currently processing
set elem [lindex $args $i]
# puts "cycle: $i (elem: $elem, status: $parser_st, first: $first)"
switch $parser_st {
state0 {
switch -- [::string tolower $elem] {
# -table and -select don't drive the parser state machine
# and whatever they have as arguments on the command
# line they're set
"-table" {
# -table -- identify which table the query is about
set table [lindex $args [incr i]]
}
"-select" {
# -select -
set what [lindex $args [incr i]]
}
"-or" -
"-and" {
if {$first} {
return -code error "$elem can not be the first element of a where clause"
} else {
incr condition_count
dict set where_expr $condition_count logical [string range $elem 1 end]
set parser_st where_op
}
}
default {
if {[::string index $elem 0] == "-"} {
if {!$first} {
incr condition_count
}
dict set where_expr $condition_count column [string range $elem 1 end]
set first 0
set parser_st where_op
} else {
return -code error "Error: expected -<column_name>"
}
}
}
}
where_op {
switch -- [string tolower $elem] {
"-lt" -
"-gt" -
"-ne" -
"-eq" {
dict set where_expr $condition_count operator [string range $elem 1 end]
set parser_st cond_predicate
}
"-null" -
"-notnull" {
dict set where_expr $condition_count operator [string range $elem 1 end]
set parser_st state0
}
default {
if {[::string index $elem 0] == "-"} {
dict set where_expr $condition_count column [string range $elem 1 end]
} else {
dict set where_expr $condition_count operator "eq"
dict set where_expr $condition_count predicate $elem
set parser_st state0
}
}
}
}
cond_predicate {
switch -- [string tolower $elem] {
"-expr" {
dict set where_expr $condition_count predicate [lindex $args [incr i]]
}
default {
# convert any asterisks to percent signs in the
# value field
regsub -all {\*} $elem {%} elem
dict set where_expr $condition_count predicate $elem
}
}
set parser_st state0
}
default {
return -code error "invalid parser status"
}
}
}
set sql "SELECT $what from $table WHERE[$this where_clause $where_expr]"
return $sql
}
}
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