github.com/bytedance/go-tagexpr/v2@v2.9.8/expr.go (about)

     1  // Copyright 2019 Bytedance Inc. All Rights Reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package tagexpr
    16  
    17  import (
    18  	"bytes"
    19  	"context"
    20  	"fmt"
    21  	"os"
    22  
    23  	"github.com/andeya/goutil"
    24  )
    25  
    26  // Expr expression
    27  type Expr struct {
    28  	expr ExprNode
    29  }
    30  
    31  // parseExpr parses the expression.
    32  func parseExpr(expr string) (*Expr, error) {
    33  	e := newGroupExprNode()
    34  	p := &Expr{
    35  		expr: e,
    36  	}
    37  	s := expr
    38  	err := p.parseExprNode(&s, e)
    39  	if err != nil {
    40  		return nil, err
    41  	}
    42  	sortPriority(e)
    43  	return p, nil
    44  }
    45  func (p *Expr) parseExprNode(expr *string, e ExprNode) error {
    46  	trimLeftSpace(expr)
    47  	if *expr == "" {
    48  		return nil
    49  	}
    50  	operand := p.readSelectorExprNode(expr)
    51  	if operand == nil {
    52  		operand = p.readRangeKvExprNode(expr)
    53  		if operand == nil {
    54  			var subExprNode *string
    55  			operand, subExprNode = readGroupExprNode(expr)
    56  			if operand != nil {
    57  				err := p.parseExprNode(subExprNode, operand)
    58  				if err != nil {
    59  					return err
    60  				}
    61  			} else {
    62  				operand = p.parseOperand(expr)
    63  			}
    64  		}
    65  	}
    66  	if operand == nil {
    67  		return fmt.Errorf("syntax error: %q", *expr)
    68  	}
    69  	trimLeftSpace(expr)
    70  	operator := p.parseOperator(expr)
    71  	if operator == nil {
    72  		e.SetRightOperand(operand)
    73  		operand.SetParent(e)
    74  		return nil
    75  	}
    76  	if _, ok := e.(*groupExprNode); ok {
    77  		operator.SetLeftOperand(operand)
    78  		operand.SetParent(operator)
    79  		e.SetRightOperand(operator)
    80  		operator.SetParent(e)
    81  	} else {
    82  		operator.SetParent(e.Parent())
    83  		operator.Parent().SetRightOperand(operator)
    84  		operator.SetLeftOperand(e)
    85  		e.SetParent(operator)
    86  		e.SetRightOperand(operand)
    87  		operand.SetParent(e)
    88  	}
    89  	return p.parseExprNode(expr, operator)
    90  }
    91  
    92  func (p *Expr) parseOperand(expr *string) (e ExprNode) {
    93  	for _, fn := range funcList {
    94  		if e = fn(p, expr); e != nil {
    95  			return e
    96  		}
    97  	}
    98  	if e = readStringExprNode(expr); e != nil {
    99  		return e
   100  	}
   101  	if e = readDigitalExprNode(expr); e != nil {
   102  		return e
   103  	}
   104  	if e = readBoolExprNode(expr); e != nil {
   105  		return e
   106  	}
   107  	if e = readNilExprNode(expr); e != nil {
   108  		return e
   109  	}
   110  	return nil
   111  }
   112  
   113  func (*Expr) parseOperator(expr *string) (e ExprNode) {
   114  	s := *expr
   115  	if len(s) < 2 {
   116  		return nil
   117  	}
   118  	defer func() {
   119  		if e != nil && *expr == s {
   120  			*expr = (*expr)[2:]
   121  		}
   122  	}()
   123  	a := s[:2]
   124  	switch a {
   125  	// case "<<":
   126  	// case ">>":
   127  	// case "&^":
   128  	case "||":
   129  		return newOrExprNode()
   130  	case "&&":
   131  		return newAndExprNode()
   132  	case "==":
   133  		return newEqualExprNode()
   134  	case ">=":
   135  		return newGreaterEqualExprNode()
   136  	case "<=":
   137  		return newLessEqualExprNode()
   138  	case "!=":
   139  		return newNotEqualExprNode()
   140  	}
   141  	defer func() {
   142  		if e != nil {
   143  			*expr = (*expr)[1:]
   144  		}
   145  	}()
   146  	switch a[0] {
   147  	// case '&':
   148  	// case '|':
   149  	// case '^':
   150  	case '+':
   151  		return newAdditionExprNode()
   152  	case '-':
   153  		return newSubtractionExprNode()
   154  	case '*':
   155  		return newMultiplicationExprNode()
   156  	case '/':
   157  		return newDivisionExprNode()
   158  	case '%':
   159  		return newRemainderExprNode()
   160  	case '<':
   161  		return newLessExprNode()
   162  	case '>':
   163  		return newGreaterExprNode()
   164  	}
   165  	return nil
   166  }
   167  
   168  // run calculates the value of expression.
   169  func (p *Expr) run(field string, tagExpr *TagExpr) interface{} {
   170  	return p.expr.Run(context.Background(), field, tagExpr)
   171  }
   172  
   173  /**
   174   * Priority:
   175   * () ! bool float64 string nil
   176   * * / %
   177   * + -
   178   * < <= > >=
   179   * == !=
   180   * &&
   181   * ||
   182  **/
   183  
   184  func sortPriority(e ExprNode) {
   185  	printExprNode(e)
   186  	for subSortPriority(e.RightOperand(), false) {
   187  		printExprNode(e)
   188  	}
   189  }
   190  
   191  func subSortPriority(e ExprNode, isLeft bool) bool {
   192  	if e == nil {
   193  		return false
   194  	}
   195  	leftChanged := subSortPriority(e.LeftOperand(), true)
   196  	rightChanged := subSortPriority(e.RightOperand(), false)
   197  	if getPriority(e) > getPriority(e.LeftOperand()) {
   198  		printf("before:\n")
   199  		printExprNode(e)
   200  		leftOperandToParent(e, isLeft)
   201  		printf("after:\n")
   202  		printExprNode(e.Parent())
   203  		return true
   204  	}
   205  	return leftChanged || rightChanged
   206  }
   207  
   208  func leftOperandToParent(e ExprNode, isLeft bool) {
   209  	le := e.LeftOperand()
   210  	if le == nil {
   211  		return
   212  	}
   213  	p := e.Parent()
   214  	le.SetParent(p)
   215  	if p != nil {
   216  		if isLeft {
   217  			p.SetLeftOperand(le)
   218  		} else {
   219  			p.SetRightOperand(le)
   220  		}
   221  	}
   222  	e.SetParent(le)
   223  	e.SetLeftOperand(le.RightOperand())
   224  	le.RightOperand().SetParent(e)
   225  	le.SetRightOperand(e)
   226  }
   227  
   228  func getPriority(e ExprNode) (i int) {
   229  	// defer func() {
   230  	// 	printf("expr:%T %d\n", e, i)
   231  	// }()
   232  	switch e.(type) {
   233  	default: // () ! bool float64 string nil
   234  		return 7
   235  	case *multiplicationExprNode, *divisionExprNode, *remainderExprNode: // * / %
   236  		return 6
   237  	case *additionExprNode, *subtractionExprNode: // + -
   238  		return 5
   239  	case *lessExprNode, *lessEqualExprNode, *greaterExprNode, *greaterEqualExprNode: // < <= > >=
   240  		return 4
   241  	case *equalExprNode, *notEqualExprNode: // == !=
   242  		return 3
   243  	case *andExprNode: // &&
   244  		return 2
   245  	case *orExprNode: // ||
   246  		return 1
   247  	}
   248  }
   249  
   250  // ExprNode expression interface
   251  type ExprNode interface {
   252  	SetParent(ExprNode)
   253  	Parent() ExprNode
   254  	LeftOperand() ExprNode
   255  	RightOperand() ExprNode
   256  	SetLeftOperand(ExprNode)
   257  	SetRightOperand(ExprNode)
   258  	String() string
   259  	Run(context.Context, string, *TagExpr) interface{}
   260  }
   261  
   262  // var _ ExprNode = new(exprBackground)
   263  
   264  type exprBackground struct {
   265  	parent       ExprNode
   266  	leftOperand  ExprNode
   267  	rightOperand ExprNode
   268  }
   269  
   270  func (eb *exprBackground) SetParent(e ExprNode) {
   271  	eb.parent = e
   272  }
   273  
   274  func (eb *exprBackground) Parent() ExprNode {
   275  	return eb.parent
   276  }
   277  
   278  func (eb *exprBackground) LeftOperand() ExprNode {
   279  	return eb.leftOperand
   280  }
   281  
   282  func (eb *exprBackground) RightOperand() ExprNode {
   283  	return eb.rightOperand
   284  }
   285  
   286  func (eb *exprBackground) SetLeftOperand(left ExprNode) {
   287  	eb.leftOperand = left
   288  }
   289  
   290  func (eb *exprBackground) SetRightOperand(right ExprNode) {
   291  	eb.rightOperand = right
   292  }
   293  
   294  func (*exprBackground) Run(context.Context, string, *TagExpr) interface{} { return nil }
   295  
   296  var debugSwitch = goutil.IsGoTest()
   297  
   298  func printf(format string, a ...interface{}) {
   299  	if debugSwitch {
   300  		fmt.Fprintf(os.Stderr, format, a...)
   301  	}
   302  }
   303  
   304  func printExprNode(node ExprNode) {
   305  	if node == nil {
   306  		return
   307  	}
   308  	tail := true
   309  	if node.Parent() != nil {
   310  		tail = node == node.Parent().RightOperand()
   311  	}
   312  	printf("%s\n\n", formatExprNode(node, 0, tail))
   313  }
   314  
   315  func formatExprNode(node ExprNode, level int, tail bool) []byte {
   316  	var b bytes.Buffer
   317  	if node == nil {
   318  	} else {
   319  		b.Write(formatExprNode(node.LeftOperand(), level+1, false))
   320  
   321  		b.Write(bytes.Repeat([]byte("    "), level))
   322  		if tail {
   323  			b.Write([]byte("└── "))
   324  		} else {
   325  			b.Write([]byte("┌── "))
   326  		}
   327  
   328  		b.Write([]byte(node.String()))
   329  		b.Write([]byte("\n"))
   330  
   331  		b.Write(formatExprNode(node.RightOperand(), level+1, true))
   332  	}
   333  	return b.Bytes()
   334  }