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See:
Description
| Interface Summary | |
|---|---|
| BNFTestImplementor | An interface that all BNF test implementations must implement. |
| Class Summary | |
|---|---|
| BNFAbstractTest | Abstract Backus-Naur test. |
| BNFNoFallthruTest | Represents a terminal test |
| BNFOneOfManyRequiredTest | A test in which one of the sub-tests must pass. |
| BNFOneOrMoreOptionalTest | A test in which all of the sub-tests must occur zero or more times |
| BNFOneOrMoreRequiredTest | A test in which all of the sub-tests must occur one or more times. |
| BNFOptionalTest | A test in which all sub-tests must occur zero or one time |
| BNFRequiredTest | A test in which all sub-tests must complete once |
| BNFTestableObject | An abstract wrapper class used to wrap objects such that a token may be easily retrieved |
| BNFTestResult | A class used to represent the completion status of a test. |
| Exception Summary | |
|---|---|
| BNFTestException | An exception class for the BNF test package |
Provides a general facility to verify a stream of tokens using commonly used Backus Naur tests.
The table below is a summary of Backus Naur formalism syntax.
Symbol Meaning
<element> :: "Element is composed of"
ELEMENT Required element
[ELEMENT] The element may be absent or occur once.
{ELEMENT} One of the elements in the braces must occur.
{ELEMENT}* All elements in the braces may be absent or occur one or more
times.
{ELEMENT}+ All elements in the braces must occur one or more
times.
<element> A composite element
| "Or"
The following table illustrates how specific classes map to Backus Naur
symbols.
Symbol Maps To
<element> :: BNFRequiredTest
ELEMENT BNFNoFallthruTest
[ELEMENT] BNFOptionalTest
{ELEMENT} BNFOneOfManyRequiredTest
{ELEMENT}* BNFOneOrMoreOptionalTest
{ELEMENT}+ BNFOneOrMoreRequiredTest
| No mapping required
For example the following Backus Naur statements:
<db> :: HEADER [UNITS] {<gds>|<cif>} {<property>}+ {<record>}* ENDDB
<gds> :: GDSTYPE [VERSION]
<cif> :: CIFTYPE [VERSION]
<property> :: PROPTYPE PROPVALUE
<record> :: RECTYPE [<body>] ENDREC
<body> :: VALUE [TRANSFORM]
Would map to the following java code. The for statement at
the end uses the dbT test instance to test if a stream of tokens meets
the syntax requirements defined by the test. The construction and
initialization of the token array occurs outside the scope of this snippet.
//...
int TRANSFORM = 0x00;
int VALUE = 0x01;
int ENDREC = 0x02;
int RECTYPE = 0x03;
int RECVALUE = 0x04;
int PROPTYPE = 0x05;
int PROPVALUE = 0x06;
int CIFTYPE = 0x07;
int GDSTYPE = 0x08;
int VERSION = 0x09;
int HEADER = 0x0A;
int UNITS = 0x0B;
int ENDDB = 0x0C;
BNFTestImplementor xfrmT = new BNFOptionalTest(new BNFTestImplementor[]{BNFNoFallthruTest(TRANSFORM)});
BNFTestImplementor valueT = new BNFNoFallthruTest(VALUE);
BNFTestImplementor[] bodyTests = {valueT, xfrmT};
BNFTestImplementor bodyT = new BNFOptionalTest(bodyTests);
BNFTestImplementor rectypeT = new BNFNoFallthruTest(RECTYPE);
BNFTestImplementor endrecT = new BNFNoFallthruTest(ENDREC);
BNFTestImplementor[] recordTests = {rectypeT, bodyT, endrecT};
BNFTestImplementor recordT = new BNFRequiredTest(recordTests);
BNFTestImplementor proptypeT = new BNFNoFallthruTest(PROPTYPE);
BNFTestImplementor propvalueT = new BNFNoFallthruTest(PROPVALUE);
BNFTestImplementor[] propertyTests = {proptypeT propvalueT};
BNFTestImplementor propertyT = new BNFRequiredTest(propertyTests);
BNFTestImplementor gdstypeT = new BNFNoFallthruTest(GDSTYPE);
BNFTestImplementor ciftypeT = new BNFNoFallthruTest(CIFTYPE);
BNFTestImplementor versionT = new BNFOptionalTest(new BNFTestImplementor[]{BNFNoFallthruTest(VERSION)});
BNFTestImplementor[] gdsTests = {gdstypeT versionT};
BNFTestImplementor[] cifTests = {ciftypeT versionT};
BNFTestImplementor gdsT = new BNFRequiredTest(gdsTests);
BNFTestImplementor cifT = new BNFRequiredTest(cifTests);
BNFTestImplementor recordG = new BNFOneOrMoreOptionalTest(
new BNFTestImplementor[] { recordT });
BNFTestImplementor propertyG = new BNFOneOrMoreRequiredTest(
new BNFTestImplementor[] { propertyT });
BNFTestImplementor typeG = new BNFOneOfManyRequiredTest(
new BNFTestImplementor[] { gdsT, cifT });
BNFTestImplementor enddbT = new BNFNoFallthruTest(ENDDB);
BNFTestImplementor unitsT = new BNFOptionalTest(new BNFTestImplementor[]{BNFNoFallthruTest(UNITS)});
BNFTestImplementor headerT = new BNFNoFallthruTest(HEADER);
BNFTestImplementor[] dbTests = {
headerT, unitsT, typeG, propertyG, recordG, enddbT };
BNFTestImplementor dbT = new BNFRequiredTest(dbTests);
for(int i = 0; i < tokens.length; i++){
if(dbT.test(tokens[i]).isFailed())
return false
}
return true;
//...
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