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GeezerVison is showing github.com — sqlparser/normalizer.go at master · go-grm/sqlparser Expand file tree/ Copy pathnormalizer.goMore file actions 224 lines (201 loc) · 5.75 KB / Copy pathnormalizer.goFile metadata and controls224 lines (201 loc) · 5.75 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 /* Copyright 2017 Google Inc. 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. */ package sqlparser import ( "fmt" "gopkg.in/go-grm/sqlparser.v1/dependency/sqltypes" "gopkg.in/go-grm/sqlparser.v1/dependency/querypb" ) // Normalize changes the statement to use bind values, and // updates the bind vars to those values. The supplied prefix // is used to generate the bind var names. The function ensures // that there are no collisions with existing bind vars. // Within Select constructs, bind vars are deduped. This allows // us to identify vindex equality. Otherwise, every value is // treated as distinct. func Normalize(stmt Statement, bindVars map[string]*querypb.BindVariable, prefix string) { nz := newNormalizer(stmt, bindVars, prefix) _ = Walk(nz.WalkStatement, stmt) } type normalizer struct { stmt Statement bindVars map[string]*querypb.BindVariable prefix string reserved map[string]struct{} counter int vals map[string]string } func newNormalizer(stmt Statement, bindVars map[string]*querypb.BindVariable, prefix string) *normalizer { return &normalizer{ stmt: stmt, bindVars: bindVars, prefix: prefix, reserved: GetBindvars(stmt), counter: 1, vals: make(map[string]string), } } // WalkStatement is the top level walk function. // If it encounters a Select, it switches to a mode // where variables are deduped. func (nz *normalizer) WalkStatement(node SQLNode) (bool, error) { switch node := node.(type) { case *Select: _ = Walk(nz.WalkSelect, node) // Don't continue return false, nil case *SQLVal: nz.convertSQLVal(node) case *ComparisonExpr: nz.convertComparison(node) } return true, nil } // WalkSelect normalizes the AST in Select mode. func (nz *normalizer) WalkSelect(node SQLNode) (bool, error) { switch node := node.(type) { case *SQLVal: nz.convertSQLValDedup(node) case *ComparisonExpr: nz.convertComparison(node) } return true, nil } func (nz *normalizer) convertSQLValDedup(node *SQLVal) { // If value is too long, don't dedup. // Such values are most likely not for vindexes. // We save a lot of CPU because we avoid building // the key for them. if len(node.Val) > 256 { nz.convertSQLVal(node) return } // Make the bindvar bval := nz.sqlToBindvar(node) if bval == nil { return } // Check if there's a bindvar for that value already. var key string if bval.Type == sqltypes.VarBinary { // Prefixing strings with "'" ensures that a string // and number that have the same representation don't // collide. key = "'" + string(node.Val) } else { key = string(node.Val) } bvname, ok := nz.vals[key] if !ok { // If there's no such bindvar, make a new one. bvname = nz.newName() nz.vals[key] = bvname nz.bindVars[bvname] = bval } // Modify the AST node to a bindvar. node.Type = ValArg node.Val = append([]byte(":"), bvname...) } // convertSQLVal converts an SQLVal without the dedup. func (nz *normalizer) convertSQLVal(node *SQLVal) { bval := nz.sqlToBindvar(node) if bval == nil { return } bvname := nz.newName() nz.bindVars[bvname] = bval node.Type = ValArg node.Val = append([]byte(":"), bvname...) } // convertComparison attempts to convert IN clauses to // use the list bind var construct. If it fails, it returns // with no change made. The walk function will then continue // and iterate on converting each individual value into separate // bind vars. func (nz *normalizer) convertComparison(node *ComparisonExpr) { if node.Operator != InStr && node.Operator != NotInStr { return } tupleVals, ok := node.Right.(ValTuple) if !ok { return } // The RHS is a tuple of values. // Make a list bindvar. bvals := &querypb.BindVariable{ Type: querypb.Type_TUPLE, } for _, val := range tupleVals { bval := nz.sqlToBindvar(val) if bval == nil { return } bvals.Values = append(bvals.Values, &querypb.Value{ Type: bval.Type, Value: bval.Value, }) } bvname := nz.newName() nz.bindVars[bvname] = bvals // Modify RHS to be a list bindvar. node.Right = ListArg(append([]byte("::"), bvname...)) } func (nz *normalizer) sqlToBindvar(node SQLNode) *querypb.BindVariable { if node, ok := node.(*SQLVal); ok { var v sqltypes.Value var err error switch node.Type { case StrVal: v, err = sqltypes.NewValue(sqltypes.VarBinary, node.Val) case IntVal: v, err = sqltypes.NewValue(sqltypes.Int64, node.Val) case FloatVal: v, err = sqltypes.NewValue(sqltypes.Float64, node.Val) default: return nil } if err != nil { return nil } return sqltypes.ValueBindVariable(v) } return nil } func (nz *normalizer) newName() string { for { newName := fmt.Sprintf("%s%d", nz.prefix, nz.counter) if _, ok := nz.reserved[newName]; !ok { nz.reserved[newName] = struct{}{} return newName } nz.counter++ } } // GetBindvars returns a map of the bind vars referenced in the statement. // TODO(sougou); This function gets called again from vtgate/planbuilder. // Ideally, this should be done only once. func GetBindvars(stmt Statement) map[string]struct{} { bindvars := make(map[string]struct{}) _ = Walk(func(node SQLNode) (kontinue bool, err error) { switch node := node.(type) { case *SQLVal: if node.Type == ValArg { bindvars[string(node.Val[1:])] = struct{}{} } case ListArg: bindvars[string(node[2:])] = struct{}{} } return true, nil }, stmt) return bindvars } |
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