go_error.go

Documentation: github.com/jezek/xgb/xgbgen

     1  package main
     2  
     3  import (
     4  	"fmt"
     5  )
     6  
     7  // Error types
     8  func (e *Error) Define(c *Context) {
     9  	c.Putln("// %s is the error number for a %s.", e.ErrConst(), e.ErrConst())
    10  	c.Putln("const %s = %d", e.ErrConst(), e.Number)
    11  	c.Putln("")
    12  	c.Putln("type %s struct {", e.ErrType())
    13  	c.Putln("Sequence uint16")
    14  	c.Putln("NiceName string")
    15  	for _, field := range e.Fields {
    16  		field.Define(c)
    17  	}
    18  	c.Putln("}")
    19  	c.Putln("")
    20  
    21  	// Read defines a function that transforms a byte slice into this
    22  	// error struct.
    23  	e.Read(c)
    24  
    25  	// Makes sure this error type implements the xgb.Error interface.
    26  	e.ImplementsError(c)
    27  
    28  	// Let's the XGB event loop read this error.
    29  	c.Putln("func init() {")
    30  	if c.protocol.isExt() {
    31  		c.Putln("xgb.NewExtErrorFuncs[\"%s\"][%d] = %sNew",
    32  			c.protocol.ExtXName, e.Number, e.ErrType())
    33  	} else {
    34  		c.Putln("xgb.NewErrorFuncs[%d] = %sNew", e.Number, e.ErrType())
    35  	}
    36  	c.Putln("}")
    37  	c.Putln("")
    38  }
    39  
    40  func (e *Error) Read(c *Context) {
    41  	c.Putln("// %sNew constructs a %s value that implements xgb.Error from "+
    42  		"a byte slice.", e.ErrType(), e.ErrType())
    43  	c.Putln("func %sNew(buf []byte) xgb.Error {", e.ErrType())
    44  	c.Putln("v := %s{}", e.ErrType())
    45  	c.Putln("v.NiceName = \"%s\"", e.SrcName())
    46  	c.Putln("")
    47  	c.Putln("b := 1 // skip error determinant")
    48  	c.Putln("b += 1 // don't read error number")
    49  	c.Putln("")
    50  	c.Putln("v.Sequence = xgb.Get16(buf[b:])")
    51  	c.Putln("b += 2")
    52  	c.Putln("")
    53  	for _, field := range e.Fields {
    54  		field.Read(c, "v.")
    55  		c.Putln("")
    56  	}
    57  	c.Putln("return v")
    58  	c.Putln("}")
    59  	c.Putln("")
    60  }
    61  
    62  // ImplementsError writes functions to implement the XGB Error interface.
    63  func (e *Error) ImplementsError(c *Context) {
    64  	c.Putln("// SequenceId returns the sequence id attached to the %s error.",
    65  		e.ErrConst())
    66  	c.Putln("// This is mostly used internally.")
    67  	c.Putln("func (err %s) SequenceId() uint16 {", e.ErrType())
    68  	c.Putln("return err.Sequence")
    69  	c.Putln("}")
    70  	c.Putln("")
    71  	c.Putln("// BadId returns the 'BadValue' number if one exists for the "+
    72  		"%s error. If no bad value exists, 0 is returned.", e.ErrConst())
    73  	c.Putln("func (err %s) BadId() uint32 {", e.ErrType())
    74  	if !c.protocol.isExt() {
    75  		c.Putln("return err.BadValue")
    76  	} else {
    77  		c.Putln("return 0")
    78  	}
    79  	c.Putln("}")
    80  	c.Putln("// Error returns a rudimentary string representation of the %s "+
    81  		"error.", e.ErrConst())
    82  	c.Putln("")
    83  	c.Putln("func (err %s) Error() string {", e.ErrType())
    84  	ErrorFieldString(c, e.Fields, e.ErrConst())
    85  	c.Putln("}")
    86  	c.Putln("")
    87  }
    88  
    89  // ErrorCopy types
    90  func (e *ErrorCopy) Define(c *Context) {
    91  	c.Putln("// %s is the error number for a %s.", e.ErrConst(), e.ErrConst())
    92  	c.Putln("const %s = %d", e.ErrConst(), e.Number)
    93  	c.Putln("")
    94  	c.Putln("type %s %s", e.ErrType(), e.Old.(*Error).ErrType())
    95  	c.Putln("")
    96  
    97  	// Read defines a function that transforms a byte slice into this
    98  	// error struct.
    99  	e.Read(c)
   100  
   101  	// Makes sure this error type implements the xgb.Error interface.
   102  	e.ImplementsError(c)
   103  
   104  	// Let's the XGB know how to read this error.
   105  	c.Putln("func init() {")
   106  	if c.protocol.isExt() {
   107  		c.Putln("xgb.NewExtErrorFuncs[\"%s\"][%d] = %sNew",
   108  			c.protocol.ExtXName, e.Number, e.ErrType())
   109  	} else {
   110  		c.Putln("xgb.NewErrorFuncs[%d] = %sNew", e.Number, e.ErrType())
   111  	}
   112  	c.Putln("}")
   113  	c.Putln("")
   114  }
   115  
   116  func (e *ErrorCopy) Read(c *Context) {
   117  	c.Putln("// %sNew constructs a %s value that implements xgb.Error from "+
   118  		"a byte slice.", e.ErrType(), e.ErrType())
   119  	c.Putln("func %sNew(buf []byte) xgb.Error {", e.ErrType())
   120  	c.Putln("v := %s(%sNew(buf).(%s))",
   121  		e.ErrType(), e.Old.(*Error).ErrType(), e.Old.(*Error).ErrType())
   122  	c.Putln("v.NiceName = \"%s\"", e.SrcName())
   123  	c.Putln("return v")
   124  	c.Putln("}")
   125  	c.Putln("")
   126  }
   127  
   128  // ImplementsError writes functions to implement the XGB Error interface.
   129  func (e *ErrorCopy) ImplementsError(c *Context) {
   130  	c.Putln("// SequenceId returns the sequence id attached to the %s error.",
   131  		e.ErrConst())
   132  	c.Putln("// This is mostly used internally.")
   133  	c.Putln("func (err %s) SequenceId() uint16 {", e.ErrType())
   134  	c.Putln("return err.Sequence")
   135  	c.Putln("}")
   136  	c.Putln("")
   137  	c.Putln("// BadId returns the 'BadValue' number if one exists for the "+
   138  		"%s error. If no bad value exists, 0 is returned.", e.ErrConst())
   139  	c.Putln("func (err %s) BadId() uint32 {", e.ErrType())
   140  	if !c.protocol.isExt() {
   141  		c.Putln("return err.BadValue")
   142  	} else {
   143  		c.Putln("return 0")
   144  	}
   145  	c.Putln("}")
   146  	c.Putln("")
   147  	c.Putln("// Error returns a rudimentary string representation of the %s "+
   148  		"error.", e.ErrConst())
   149  	c.Putln("func (err %s) Error() string {", e.ErrType())
   150  	ErrorFieldString(c, e.Old.(*Error).Fields, e.ErrConst())
   151  	c.Putln("}")
   152  	c.Putln("")
   153  }
   154  
   155  // ErrorFieldString works for both Error and ErrorCopy. It assembles all of the
   156  // fields in an error and formats them into a single string.
   157  func ErrorFieldString(c *Context, fields []Field, errName string) {
   158  	c.Putln("fieldVals := make([]string, 0, %d)", len(fields))
   159  	c.Putln("fieldVals = append(fieldVals, \"NiceName: \" + err.NiceName)")
   160  	c.Putln("fieldVals = append(fieldVals, "+
   161  		"xgb.Sprintf(\"Sequence: %s\", err.Sequence))", "%d")
   162  	for _, field := range fields {
   163  		switch field.(type) {
   164  		case *PadField:
   165  			continue
   166  		default:
   167  			if field.SrcType() == "string" {
   168  				c.Putln("fieldVals = append(fieldVals, \"%s: \" + err.%s)",
   169  					field.SrcName(), field.SrcName())
   170  			} else {
   171  				format := fmt.Sprintf("xgb.Sprintf(\"%s: %s\", err.%s)",
   172  					field.SrcName(), "%d", field.SrcName())
   173  				c.Putln("fieldVals = append(fieldVals, %s)", format)
   174  			}
   175  		}
   176  	}
   177  	c.Putln("return \"%s {\" + xgb.StringsJoin(fieldVals, \", \") + \"}\"",
   178  		errName)
   179  }
   180
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