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Merge pull request #84 from krperry/while-wend
While wend addition includes tests in examples
2 parents 3c619ad + 513b99d commit cf87407

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Lines changed: 369 additions & 5 deletions

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‎README.md‎

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@@ -549,6 +549,49 @@ be replaced by the start value, it will not be evaluated.
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After the completion of the loop, the loop variable value will be the end value + step value (unless
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the loop is exited using a **GOTO** statement).
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Conditional loops are achieved through the use of **WHILE-WEND** statements. The loop continues to execute
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as long as the specified condition remains true. The condition is evaluated before each iteration, so if
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the condition is false initially, the loop body will not execute at all.
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```
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> 10 LET I = 1
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> 20 WHILE I <= 3
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> 30 PRINT "Count: "; I
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> 40 LET I = I + 1
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> 50 WEND
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> RUN
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Count: 1
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Count: 2
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Count: 3
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>
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```
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WHILE loops may be nested within one another and can also be nested within FOR loops and vice versa.
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The loop will terminate when the condition becomes false or when exited using a **GOTO** statement.
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**Example of nested WHILE loops:**
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```
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> 10 LET I = 1
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> 20 WHILE I <= 2
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> 30 PRINT "Outer: "; I
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> 40 LET J = 1
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> 50 WHILE J <= 2
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> 60 PRINT " Inner: "; J
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> 70 LET J = J + 1
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> 80 WEND
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> 90 LET I = I + 1
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> 100 WEND
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> RUN
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Outer: 1
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Inner: 1
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Inner: 2
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Outer: 2
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Inner: 1
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Inner: 2
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>
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```
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### Conditionals
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Conditionals are implemented using the **IF-THEN-ELSE** statement. The expression is evaluated and the appropriate

‎basicparser.py‎

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@@ -242,7 +242,7 @@ def __stmt(self):
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"""
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if self.__token.category in [Token.FOR, Token.IF, Token.NEXT,
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Token.ON]:
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Token.ON, Token.WHILE, Token.WEND]:
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return self.__compoundstmt()
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else:
@@ -1227,6 +1227,12 @@ def __compoundstmt(self):
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elif self.__token.category == Token.ON:
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return self.__ongosubstmt()
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elif self.__token.category == Token.WHILE:
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return self.__whilestmt()
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elif self.__token.category == Token.WEND:
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return self.__wendstmt()
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def __ifstmt(self):
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"""Parses if-then-else
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statements
@@ -1393,6 +1399,42 @@ def __nextstmt(self):
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return FlowSignal(ftype=FlowSignal.LOOP_REPEAT,floop_var=loop_variable)
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def __whilestmt(self):
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"""Parses WHILE loops
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:return: The FlowSignal to indicate that
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a WHILE loop start has been processed
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"""
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self.__advance() # Advance past WHILE token
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self.__logexpr() # Evaluate the condition
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# Save result of expression
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condition_result = self.__operand_stack.pop()
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# Check if the condition is true
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if condition_result:
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# Condition is true, execute the loop body
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return FlowSignal(ftype=FlowSignal.WHILE_BEGIN)
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else:
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# Condition is false, skip the loop
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return FlowSignal(ftype=FlowSignal.WHILE_SKIP)
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def __wendstmt(self):
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"""Processes a WEND statement that terminates
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a WHILE loop
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:return: A FlowSignal indicating that the loop
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should repeat (return to WHILE)
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"""
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self.__advance() # Advance past WEND token
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# Return signal to repeat the WHILE loop
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return FlowSignal(ftype=FlowSignal.WHILE_REPEAT)
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def __ongosubstmt(self):
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"""Process the ON-GOSUB statement
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‎basictoken.py‎

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@@ -119,6 +119,8 @@ class BASICToken:
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SEMICOLON = 86 # SEMICOLON
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LEFT = 87 # LEFT$ function
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RIGHT = 88 # RIGHT$ function
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WHILE = 89 # WHILE keyword
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WEND = 90 # WEND keyword
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# Displayable names for each token category
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catnames = ['EOF', 'LET', 'LIST', 'PRINT', 'RUN',
@@ -137,7 +139,7 @@ class BASICToken:
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'MAX', 'MIN', 'INSTR', 'AND', 'OR', 'NOT', 'PI',
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'RNDINT', 'OPEN', 'HASH', 'CLOSE', 'FSEEK', 'APPEND',
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'OUTPUT', 'RESTORE', 'RNDINT', 'TAB', 'SEMICOLON',
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'LEFT', 'RIGHT']
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'LEFT', 'RIGHT', 'WHILE', 'WEND']
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smalltokens = {'=': ASSIGNOP, '(': LEFTPAREN, ')': RIGHTPAREN,
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'+': PLUS, '-': MINUS, '*': TIMES, '/': DIVIDE,
@@ -174,7 +176,8 @@ class BASICToken:
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'CLOSE': CLOSE, 'FSEEK': FSEEK,
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'APPEND': APPEND, 'OUTPUT':OUTPUT,
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'RESTORE': RESTORE, 'TAB': TAB,
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'LEFT$': LEFT, 'RIGHT$': RIGHT}
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'LEFT$': LEFT, 'RIGHT$': RIGHT,
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'WHILE': WHILE, 'WEND': WEND}
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# Functions

‎examples/while_tests.bas‎

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1 REM ===============================================
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2 REM WHILE-WEND LOOP COMPREHENSIVE TEST SUITE
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3 REM ===============================================
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4 REM
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5 REM This program tests all aspects of WHILE-WEND
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6 REM loop functionality in PyBasic
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7 REM ===============================================
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8 REM
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10 PRINT "=== WHILE-WEND Loop Test Suite ==="
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20 PRINT ""
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21 REM
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22 REM ===============================================
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23 REM Test 1: Basic WHILE Loop
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24 REM ===============================================
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30 PRINT "Test 1: Basic WHILE Loop"
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40 PRINT "Expected: Count 1 through 5"
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50 PRINT "------------------------"
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60 LET I = 1
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70 WHILE I <= 5
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80 PRINT "Count: "; I
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90 LET I = I + 1
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100 WEND
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110 PRINT "Basic WHILE loop completed"
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120 PRINT ""
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121 REM
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122 REM ===============================================
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123 REM Test 2: WHILE Loop with False Condition
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124 REM ===============================================
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130 PRINT "Test 2: WHILE Loop Skip Test"
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140 PRINT "Expected: Only skip message, no loop output"
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150 PRINT "----------------------------------------"
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160 LET X = 10
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170 WHILE X < 5
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180 PRINT "This should NOT print!"
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190 WEND
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200 PRINT "WHILE loop was correctly skipped"
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210 PRINT ""
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211 REM
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212 REM ===============================================
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213 REM Test 3: Nested WHILE Loops
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214 REM ===============================================
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220 PRINT "Test 3: Nested WHILE Loops"
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230 PRINT "Expected: Outer 1-3, Inner 1-2 for each"
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240 PRINT "-------------------------------------"
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250 LET I = 1
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260 WHILE I <= 3
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270 PRINT "Outer loop: "; I
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280 LET J = 1
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290 WHILE J <= 2
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300 PRINT " Inner loop: "; J
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310 LET J = J + 1
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320 WEND
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330 LET I = I + 1
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340 WEND
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350 PRINT "Nested WHILE loops completed"
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360 PRINT ""
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361 REM
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362 REM ===============================================
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363 REM Test 4: WHILE with Complex Conditions
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364 REM ===============================================
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370 PRINT "Test 4: Complex Condition Test"
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380 PRINT "Expected: A=1,B=5 through A=3,B=5"
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390 PRINT "--------------------------------"
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400 LET A = 1
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410 LET B = 5
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420 WHILE A < B AND A < 4
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430 PRINT "A = "; A; ", B = "; B
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440 LET A = A + 1
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450 WEND
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460 PRINT "Complex condition test completed"
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470 PRINT ""
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471 REM
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472 REM ===============================================
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473 REM Test 5: WHILE Loop with Countdown
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474 REM ===============================================
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480 PRINT "Test 5: Countdown WHILE Loop"
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490 PRINT "Expected: Countdown from 5 to 1"
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500 PRINT "-----------------------------"
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510 LET COUNT = 5
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520 WHILE COUNT > 0
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530 PRINT "Countdown: "; COUNT
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540 LET COUNT = COUNT - 1
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550 WEND
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560 PRINT "Countdown completed!"
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570 PRINT ""
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571 REM
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572 REM ===============================================
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573 REM Test 6: WHILE with String Variables
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574 REM ===============================================
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580 PRINT "Test 6: WHILE with String Conditions"
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590 PRINT "Expected: Process items until STOP"
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600 PRINT "--------------------------------"
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610 LET ITEM$ = "START"
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620 LET COUNTER = 0
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630 WHILE ITEM$ <> "STOP"
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640 LET COUNTER = COUNTER + 1
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650 PRINT "Processing item "; COUNTER
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660 IF COUNTER = 3 THEN LET ITEM$ = "STOP"
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670 WEND
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680 PRINT "String condition test completed"
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690 PRINT ""
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691 REM
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692 REM ===============================================
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693 REM Test 7: Mixed FOR and WHILE Loops
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694 REM ===============================================
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700 PRINT "Test 7: Mixed FOR and WHILE Loops"
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710 PRINT "Expected: FOR loop with nested WHILE"
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720 PRINT "--------------------------------"
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730 FOR K = 1 TO 2
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740 PRINT "FOR loop iteration: "; K
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750 LET M = 1
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760 WHILE M <= 2
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770 PRINT " WHILE iteration: "; M
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780 LET M = M + 1
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790 WEND
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800 NEXT K
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810 PRINT "Mixed loop test completed"
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820 PRINT ""
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821 REM
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822 REM ===============================================
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823 REM Test 8: WHILE with Mathematical Operations
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824 REM ===============================================
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830 PRINT "Test 8: WHILE with Math Operations"
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840 PRINT "Expected: Powers of 2 up to 16"
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850 PRINT "-----------------------------"
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860 LET POWER = 1
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870 WHILE POWER <= 16
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880 PRINT "2^"; LOG(POWER)/LOG(2); " = "; POWER
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890 LET POWER = POWER * 2
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900 WEND
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910 PRINT "Mathematical operations test completed"
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920 PRINT ""
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921 REM
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922 REM ===============================================
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923 REM Final Summary
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924 REM ===============================================
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930 PRINT "======================================="
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940 PRINT "ALL WHILE-WEND TESTS COMPLETED!"
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950 PRINT "If you see this message, all tests"
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960 PRINT "have executed successfully!"
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970 PRINT "======================================="
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975 REM
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976 REM ===============================================
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977 REM Test 9: WHILE-WEND Validation Tests
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978 REM ===============================================
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980 PRINT "Test 9: WHILE-WEND Validation"
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985 PRINT "Expected: Tests that require proper structure"
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990 PRINT "--------------------------------------------"
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1000 PRINT "Note: Missing WEND validation occurs at load time"
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1010 PRINT "GOTO breaking WHILE loops causes runtime errors"
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1020 PRINT "This ensures proper WHILE-WEND structure"
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1030 PRINT "Validation tests completed"
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1040 PRINT ""
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1050 PRINT "======================================="
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1060 PRINT "ALL WHILE-WEND TESTS COMPLETED!"
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1070 PRINT "VALIDATION: Missing WEND detected at load"
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1080 PRINT "VALIDATION: GOTO in WHILE causes error"
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1090 PRINT "All features working correctly!"
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1100 PRINT "======================================="
160+
1110 END

‎flowsignal.py‎

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@@ -76,6 +76,18 @@ class FlowSignal:
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# Indicates that a conditional result block should be executed
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EXECUTE = 7
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# Indicates the start of a WHILE loop where the condition
80+
# is true and the loop body should be executed
81+
WHILE_BEGIN = 8
82+
83+
# Indicates the end of a WHILE loop and that execution should
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# return to the beginning of the loop to re-evaluate the condition
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WHILE_REPEAT = 9
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87+
# Indicates that a WHILE loop should be skipped because
88+
# the condition is false
89+
WHILE_SKIP = 10
90+
7991
def __init__(self, ftarget=None, ftype=SIMPLE_JUMP, floop_var=None):
8092
"""Creates a new FlowSignal for a branch. If the jump
8193
target is supplied, then the branch is assumed to be
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94106
if ftype not in [self.GOSUB, self.SIMPLE_JUMP, self.LOOP_BEGIN,
95107
self.LOOP_REPEAT, self.RETURN,
96-
self.LOOP_SKIP, self.STOP, self.EXECUTE]:
108+
self.LOOP_SKIP, self.STOP, self.EXECUTE,
109+
self.WHILE_BEGIN, self.WHILE_REPEAT, self.WHILE_SKIP]:
97110
raise TypeError("Invalid flow signal type supplied: " + str(ftype))
98111

99112
if ftarget == None and \
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103116
if ftarget != None and \
104117
ftype in [self.RETURN, self.LOOP_BEGIN, self.LOOP_REPEAT,
105-
self.STOP, self.EXECUTE]:
118+
self.STOP, self.EXECUTE, self.WHILE_BEGIN,
119+
self.WHILE_REPEAT]:
106120
raise TypeError("Target wrongly supplied for flow signal " + str(ftype))
107121

108122
self.ftype = ftype

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