github.com/matrixorigin/matrixone@v0.7.0/pkg/sql/parsers/tree/format.go (about)

     1  // Copyright 2021 Matrix Origin
     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 tree
    16  
    17  import (
    18  	"fmt"
    19  	"strings"
    20  
    21  	"github.com/matrixorigin/matrixone/pkg/sql/parsers/dialect"
    22  )
    23  
    24  // FmtCtx contains formatted text of the node.
    25  type FmtCtx struct {
    26  	*strings.Builder
    27  	dialectType dialect.DialectType
    28  	// quoteString string
    29  	quoteString       bool
    30  	singleQuoteString bool
    31  }
    32  
    33  func NewFmtCtx(dialectType dialect.DialectType, opts ...FmtCtxOption) *FmtCtx {
    34  	ctx := &FmtCtx{
    35  		Builder:     new(strings.Builder),
    36  		dialectType: dialectType,
    37  	}
    38  	for _, opt := range opts {
    39  		opt.Apply(ctx)
    40  	}
    41  	return ctx
    42  }
    43  
    44  type FmtCtxOption func(*FmtCtx)
    45  
    46  func (f FmtCtxOption) Apply(ctx *FmtCtx) {
    47  	f(ctx)
    48  }
    49  
    50  func WithQuoteString(quote bool) FmtCtxOption {
    51  	return FmtCtxOption(func(ctx *FmtCtx) {
    52  		ctx.quoteString = quote
    53  	})
    54  }
    55  func WithSingleQuoteString() FmtCtxOption {
    56  	return FmtCtxOption(func(ctx *FmtCtx) {
    57  		ctx.singleQuoteString = true
    58  	})
    59  }
    60  
    61  // NodeFormatter for formatted output of the node.
    62  type NodeFormatter interface {
    63  	Format(ctx *FmtCtx)
    64  }
    65  
    66  func String(node NodeFormatter, dialectType dialect.DialectType) string {
    67  	if node == nil {
    68  		return "<nil>"
    69  	}
    70  
    71  	ctx := NewFmtCtx(dialectType)
    72  	node.Format(ctx)
    73  	return ctx.String()
    74  }
    75  
    76  func (ctx *FmtCtx) PrintExpr(currentExpr Expr, expr Expr, left bool) {
    77  	if precedenceFor(currentExpr) == Syntactic {
    78  		expr.Format(ctx)
    79  	} else {
    80  		needParens := needParens(currentExpr, expr, left)
    81  		if needParens {
    82  			ctx.WriteByte('(')
    83  		}
    84  		expr.Format(ctx)
    85  		if needParens {
    86  			ctx.WriteByte(')')
    87  		}
    88  	}
    89  }
    90  
    91  func (ctx *FmtCtx) WriteValue(t P_TYPE, v string) (int, error) {
    92  	if ctx.quoteString {
    93  		switch t {
    94  		case P_char:
    95  			return ctx.WriteString(fmt.Sprintf("%q", v))
    96  		default:
    97  			return ctx.WriteString(v)
    98  		}
    99  	}
   100  	if ctx.singleQuoteString && t == P_char {
   101  		return ctx.WriteString(fmt.Sprintf("'%s'", v))
   102  	}
   103  	return ctx.WriteString(v)
   104  }
   105  
   106  func (ctx *FmtCtx) WriteStringQuote(v string) (int, error) {
   107  	if ctx.quoteString {
   108  		return ctx.WriteString(fmt.Sprintf("%q", v))
   109  	} else {
   110  		return ctx.WriteString(v)
   111  	}
   112  }
   113  
   114  // needParens says if we need a parenthesis
   115  // op is the operator we are printing
   116  // val is the value we are checking if we need parens around or not
   117  // left let's us know if the value is on the lhs or rhs of the operator
   118  func needParens(op, val Expr, left bool) bool {
   119  	// Values are atomic and never need parens
   120  	if IsValue(val) {
   121  		return false
   122  	}
   123  
   124  	if areBothISExpr(op, val) {
   125  		return true
   126  	}
   127  
   128  	opBinding := precedenceFor(op)
   129  	valBinding := precedenceFor(val)
   130  
   131  	if opBinding == Syntactic || valBinding == Syntactic {
   132  		return false
   133  	}
   134  
   135  	if left {
   136  		// for left associative operators, if the value is to the left of the operator,
   137  		// we only need parens if the order is higher for the value expression
   138  		return valBinding > opBinding
   139  	}
   140  
   141  	return valBinding >= opBinding
   142  }
   143  
   144  // IsValue returns true if the Expr is a string, integral or value arg.
   145  // NULL is not considered to be a value.
   146  func IsValue(node Expr) bool {
   147  	switch node.(type) {
   148  	case *NumVal, *StrVal:
   149  		return true
   150  	}
   151  	return false
   152  }
   153  
   154  func areBothISExpr(op Expr, val Expr) bool {
   155  	// when using IS on an IS op, we need special handling
   156  	_, isOpIs := op.(*IsNullExpr)
   157  	if isOpIs {
   158  		_, isValIs := val.(*IsNullExpr)
   159  		if isValIs {
   160  			return true
   161  		}
   162  	}
   163  	_, isOpIsNot := op.(*IsNullExpr)
   164  	if isOpIsNot {
   165  		_, isValIsNot := val.(*IsNullExpr)
   166  		if isValIsNot {
   167  			return true
   168  		}
   169  	}
   170  	return false
   171  }