342 lines
9.5 KiB
Go
342 lines
9.5 KiB
Go
/* WIP Under Construction */
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package main
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//import "fmt"
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import "strings"
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import "os"
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func _process_columns(colstr string) (columns []DB_Column) {
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if colstr == "" {
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return columns
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}
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colstr = strings.Replace(colstr," as "," AS ",-1)
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for _, segment := range strings.Split(colstr,",") {
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var outcol DB_Column
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dothalves := strings.Split(strings.TrimSpace(segment),".")
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var halves []string
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if len(dothalves) == 2 {
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outcol.Table = dothalves[0]
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halves = strings.Split(dothalves[1]," AS ")
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} else {
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halves = strings.Split(dothalves[0]," AS ")
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}
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halves[0] = strings.TrimSpace(halves[0])
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if len(halves) == 2 {
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outcol.Alias = strings.TrimSpace(halves[1])
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}
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if halves[0][len(halves[0]) - 1] == ')' {
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outcol.Type = "function"
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} else {
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outcol.Type = "column"
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}
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outcol.Left = halves[0]
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columns = append(columns,outcol)
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}
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return columns
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}
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func _process_orderby(orderstr string) (order []DB_Order) {
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if orderstr == "" {
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return order
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}
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for _, segment := range strings.Split(orderstr,",") {
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var outorder DB_Order
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halves := strings.Split(strings.TrimSpace(segment)," ")
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if len(halves) != 2 {
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continue
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}
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outorder.Column = halves[0]
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outorder.Order = strings.ToLower(halves[1])
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order = append(order,outorder)
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}
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return order
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}
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func _process_joiner(joinstr string) (joiner []DB_Joiner) {
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if joinstr == "" {
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return joiner
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}
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joinstr = strings.Replace(joinstr," on "," ON ",-1)
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joinstr = strings.Replace(joinstr," and "," AND ",-1)
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for _, segment := range strings.Split(joinstr," AND ") {
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var outjoin DB_Joiner
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var parseOffset int
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var left, right string
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left, parseOffset = _get_identifier(segment, parseOffset)
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outjoin.Operator, parseOffset = _get_operator(segment, parseOffset + 1)
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right, parseOffset = _get_identifier(segment, parseOffset + 1)
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left_column := strings.Split(left,".")
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right_column := strings.Split(right,".")
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outjoin.LeftTable = strings.TrimSpace(left_column[0])
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outjoin.RightTable = strings.TrimSpace(right_column[0])
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outjoin.LeftColumn = strings.TrimSpace(left_column[1])
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outjoin.RightColumn = strings.TrimSpace(right_column[1])
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joiner = append(joiner,outjoin)
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}
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return joiner
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}
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// TO-DO: Add support for keywords like BETWEEN. We'll probably need an arbitrary expression parser like with the update setters.
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func _process_where(wherestr string) (where []DB_Where) {
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if wherestr == "" {
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return where
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}
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wherestr = strings.Replace(wherestr," and "," AND ",-1)
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for _, segment := range strings.Split(wherestr," AND ") {
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// TO-DO: Subparse the contents of a function and spit out a DB_Function struct
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var outwhere DB_Where
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var parseOffset int
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var left, right string
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left, parseOffset = _get_identifier(segment, parseOffset)
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outwhere.Operator, parseOffset = _get_operator(segment, parseOffset + 1)
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right, parseOffset = _get_identifier(segment, parseOffset + 1)
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outwhere.LeftType = _get_identifier_type(left)
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outwhere.RightType = _get_identifier_type(right)
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left_operand := strings.Split(left,".")
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right_operand := strings.Split(right,".")
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if len(left_operand) == 2 {
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outwhere.LeftTable = strings.TrimSpace(left_operand[0])
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outwhere.LeftColumn = strings.TrimSpace(left_operand[1])
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} else {
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outwhere.LeftColumn = strings.TrimSpace(left_operand[0])
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}
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if len(right_operand) == 2 {
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outwhere.RightTable = strings.TrimSpace(right_operand[0])
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outwhere.RightColumn = strings.TrimSpace(right_operand[1])
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} else {
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outwhere.RightColumn = strings.TrimSpace(right_operand[0])
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}
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where = append(where,outwhere)
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}
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return where
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}
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func _process_set(setstr string) (setter []DB_Setter) {
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if setstr == "" {
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return setter
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}
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//fmt.Println("setstr",setstr)
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// First pass, splitting the string by commas while ignoring the innards of functions
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var setset []string
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var buffer string
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var last_item int
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setstr += ","
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for i := 0; i < len(setstr); i++ {
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if setstr[i] == '(' {
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i = _skip_function_call(setstr,i-1)
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setset = append(setset,setstr[last_item:i+1])
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buffer = ""
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last_item = i + 2
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} else if setstr[i] == ',' && buffer != "" {
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setset = append(setset,buffer)
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buffer = ""
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last_item = i + 1
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} else if (setstr[i] > 32) && setstr[i] != ',' && setstr[i] != ')' {
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buffer += string(setstr[i])
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}
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}
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// Second pass. Break this setitem into manageable chunks
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buffer = ""
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for _, setitem := range setset {
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var tmp_setter DB_Setter
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halves := strings.Split(setitem,"=")
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if len(halves) != 2 {
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continue
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}
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tmp_setter.Column = strings.TrimSpace(halves[0])
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halves[1] += ")"
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var optype int // 0: None, 1: Number, 2: Column, 3: Function, 4: String, 5: Operator
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//fmt.Println("halves[1]",halves[1])
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for i := 0; i < len(halves[1]); i++ {
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char := halves[1][i]
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//fmt.Println("optype",optype)
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switch(optype) {
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case 0: // unknown
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if ('0' <= char && char <= '9') {
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optype = 1
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buffer = string(char)
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} else if ('a' <= char && char <= 'z') || ('A' <= char && char <= 'Z') {
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optype = 2
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buffer = string(char)
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} else if char == '\'' {
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optype = 4
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} else if _is_op_byte(char) {
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optype = 5
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buffer = string(char)
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} else if char == '?' {
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//fmt.Println("Expr:","?")
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tmp_setter.Expr = append(tmp_setter.Expr,DB_Token{"?","substitute"})
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}
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case 1: // number
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if ('0' <= char && char <= '9') {
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buffer += string(char)
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} else {
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optype = 0
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i--
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//fmt.Println("Expr:",buffer)
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tmp_setter.Expr = append(tmp_setter.Expr,DB_Token{buffer,"number"})
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}
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case 2: // column
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if ('a' <= char && char <= 'z') || ('A' <= char && char <= 'Z') {
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buffer += string(char)
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} else if char == '(' {
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optype = 3
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i--
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} else {
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optype = 0
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i--
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//fmt.Println("Expr:",buffer)
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tmp_setter.Expr = append(tmp_setter.Expr,DB_Token{buffer,"column"})
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}
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case 3: // function
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var pre_i int = i
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//fmt.Println("buffer",buffer)
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//fmt.Println("len(halves)",len(halves[1]))
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//fmt.Println("pre_i",string(halves[1][pre_i]))
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//fmt.Println("msg prior to pre_i",halves[1][0:pre_i])
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i = _skip_function_call(halves[1],i-1)
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//fmt.Println("i",i)
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//fmt.Println("msg prior to i-1",halves[1][0:i-1])
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//fmt.Println("string(i-1)",string(halves[1][i-1]))
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//fmt.Println("string(i)",string(halves[1][i]))
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buffer += halves[1][pre_i:i] + string(halves[1][i])
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//fmt.Println("Expr:",buffer)
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tmp_setter.Expr = append(tmp_setter.Expr,DB_Token{buffer,"function"})
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optype = 0
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case 4: // string
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if char != '\'' {
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buffer += string(char)
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} else {
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optype = 0
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//fmt.Println("Expr:",buffer)
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tmp_setter.Expr = append(tmp_setter.Expr,DB_Token{buffer,"string"})
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}
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case 5: // operator
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if _is_op_byte(char) {
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buffer += string(char)
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} else {
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optype = 0
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i--
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//fmt.Println("Expr:",buffer)
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tmp_setter.Expr = append(tmp_setter.Expr,DB_Token{buffer,"operator"})
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}
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}
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}
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setter = append(setter,tmp_setter)
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}
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//fmt.Println("setter",setter)
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return setter
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}
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func _is_op_byte(char byte) bool {
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return char == '<' || char == '>' || char == '=' || char == '!' || char == '*' || char == '%' || char == '+' || char == '-' || char == '/'
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}
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func _process_fields(fieldstr string) (fields []DB_Field) {
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if fieldstr == "" {
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return fields
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}
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var buffer string
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var last_item int
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fieldstr += ","
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for i := 0; i < len(fieldstr); i++ {
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if fieldstr[i] == '(' {
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i = _skip_function_call(fieldstr,i-1)
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fields = append(fields,DB_Field{Name:fieldstr[last_item:i+1],Type:_get_identifier_type(fieldstr[last_item:i+1])})
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buffer = ""
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last_item = i + 2
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} else if fieldstr[i] == ',' && buffer != "" {
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fields = append(fields,DB_Field{Name:buffer,Type:_get_identifier_type(buffer)})
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buffer = ""
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last_item = i + 1
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} else if (fieldstr[i] > 32) && fieldstr[i] != ',' && fieldstr[i] != ')' {
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buffer += string(fieldstr[i])
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}
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}
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return fields
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}
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func _get_identifier_type(identifier string) string {
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if ('a' <= identifier[0] && identifier[0] <= 'z') || ('A' <= identifier[0] && identifier[0] <= 'Z') {
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if identifier[len(identifier) - 1] == ')' {
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return "function"
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}
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return "column"
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}
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if identifier[0] == '\'' || identifier[0] == '"' {
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return "string"
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}
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return "literal"
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}
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func _get_identifier(segment string, startOffset int) (out string, i int) {
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segment = strings.TrimSpace(segment)
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segment += " " // Avoid overflow bugs with slicing
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for i = startOffset; i < len(segment); i++ {
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if segment[i] == '(' {
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i = _skip_function_call(segment,i)
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return strings.TrimSpace(segment[startOffset:i]), (i - 1)
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}
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if (segment[i] == ' ' || _is_op_byte(segment[i])) && i != startOffset {
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return strings.TrimSpace(segment[startOffset:i]), (i - 1)
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}
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}
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return strings.TrimSpace(segment[startOffset:]), (i - 1)
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}
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func _get_operator(segment string, startOffset int) (out string, i int) {
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segment = strings.TrimSpace(segment)
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segment += " " // Avoid overflow bugs with slicing
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for i = startOffset; i < len(segment); i++ {
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if !_is_op_byte(segment[i]) && i != startOffset {
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return strings.TrimSpace(segment[startOffset:i]), (i - 1)
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}
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}
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return strings.TrimSpace(segment[startOffset:]), (i - 1)
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}
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func _skip_function_call(data string, index int) int {
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var brace_count int
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for ;index < len(data); index++{
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char := data[index]
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if char == '(' {
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brace_count++
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} else if char == ')' {
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brace_count--
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if brace_count == 0 {
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return index
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}
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}
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}
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return index
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}
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func write_file(name string, content string) (err error) {
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f, err := os.Create(name)
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if err != nil {
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return err
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}
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_, err = f.WriteString(content)
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if err != nil {
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return err
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}
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f.Sync()
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f.Close()
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return
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}
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