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Compiler/lexical analyzer: Difference between revisions
Add Forth implementation of task
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</pre>
</b>
=={{header|Forth}}==
Tested with Gforth 0.7.3.
<lang Forth>CREATE BUF 0 , \ single-character look-ahead buffer
CREATE COLUMN# 0 ,
CREATE LINE# 1 ,
: NEWLINE? ( c -- t|f) DUP 10 = SWAP 13 = OR ;
: +IN ( c --)
1 SWAP NEWLINE?
IF 0 COLUMN# ! LINE# ELSE COLUMN# THEN
+! 0 BUF ! ;
: PEEK BUF @ 0= IF STDIN KEY-FILE BUF ! THEN BUF @ ;
: GETC PEEK DUP +IN ;
: SKIP GETC DROP ;
: .LOCATION 7 .R 4 .R SPACE ;
: WHERE COLUMN# @ LINE# @ ;
: .WHERE WHERE .LOCATION ;
: .WHERE+ WHERE SWAP 1+ SWAP .LOCATION ;
: EXPECT GETC OVER OVER =
IF 2DROP
ELSE CR ." stdin:" COLUMN# @ 0 LINE# @ 0
<# #s #> TYPE ." :" <# #s #> TYPE ." : "
." unexpected `" EMIT ." ', expecting `" EMIT ." '" CR
BYE
THEN ;
: EQ PEEK [CHAR] = = IF SKIP 2SWAP THEN
." Op_" TYPE CR 2DROP ;
CREATE ESC 4 C, CHAR $ C, CHAR $ C, CHAR \ C, 0 C,
: ?ESC? CR ." Unknown escape sequence `\" EMIT ." '" CR BYE ;
: >ESC ESC 4 + C! ESC ;
: $$\n 10 ;
: $$\\ [CHAR] \ ;
: ESCAPE DUP >ESC FIND IF NIP EXECUTE ELSE DROP ?ESC? THEN ;
: ?ESCAPE DUP [CHAR] \ = IF DROP GETC ESCAPE THEN ;
: ?EOF DUP 4 = IF CR ." End-of-file in string" CR BYE THEN ;
: ?EOL DUP NEWLINE?
IF CR ." End-of-line in string" CR BYE THEN ;
: STRING PAD
BEGIN GETC ?EOF ?EOL DUP [CHAR] " <>
WHILE OVER C! CHAR+
REPEAT DROP PAD TUCK - ;
: "TYPE" [CHAR] " EMIT TYPE [CHAR] " EMIT ;
CREATE TOKEN 4 C, CHAR $ C, CHAR $ C, 0 C, 0 C,
: >HEX DUP 9 > IF 7 + THEN [CHAR] 0 + ;
: HI! $F0 AND 2/ 2/ 2/ 2/ >HEX TOKEN 3 + C! ;
: LO! $0F AND >HEX TOKEN 4 + C! ;
: >TOKEN DUP HI! LO! TOKEN ;
: ?EOF DUP 4 = IF CR ." End-of-file in comment" CR BYE THEN ;
: $$2F PEEK [CHAR] * =
IF SKIP
BEGIN
GETC ?EOF [CHAR] * =
PEEK [CHAR] / = AND
UNTIL SKIP
ELSE .WHERE ." Op_divide" CR THEN ;
: $$22 .WHERE ." String " STRING "TYPE" CR ;
: $$27 .WHERE GETC ?ESCAPE ." Integer " . [CHAR] ' EXPECT CR ;
: $$04 .WHERE ." End_of_input" CR BYE ;
: $$2D .WHERE ." Op_subtract" CR ;
: $$2B .WHERE ." Op_add" CR ;
: $$25 .WHERE ." Op_mod" CR ;
: $$2A .WHERE ." Op_multiply" CR ;
: $$7B .WHERE ." LeftBrace" CR ;
: $$7D .WHERE ." RightBrace" CR ;
: $$2C .WHERE ." Comma" CR ;
: $$29 .WHERE ." RightParen" CR ;
: $$28 .WHERE ." LeftParen" CR ;
: $$3B .WHERE ." Semicolon" CR ;
: $$3D .WHERE s" equal" s" assign" EQ ;
: $$21 .WHERE s" notequal" s" not" EQ ;
: $$3C .WHERE s" lessequal" s" less" EQ ;
: $$3E .WHERE s" greaterequal" s" greater" EQ ;
: $$26 .WHERE [CHAR] & EXPECT ." Op_and" CR ;
: $$7C .WHERE [CHAR] | EXPECT ." Op_or" CR ;
: $$20 ; \ space
CREATE KEYWORD 0 C, CHAR $ C, CHAR $ C, 5 CHARS ALLOT
: >KEYWORD DUP 2 + KEYWORD C!
KEYWORD 3 + SWAP CMOVE KEYWORD ;
: FIND-KW DUP 5 <=
IF 2DUP >KEYWORD FIND
IF TRUE 2SWAP 2DROP ELSE DROP FALSE THEN
ELSE FALSE THEN ;
: $$if ." Keyword_if" ;
: $$else ." Keyword_else" ;
: $$while ." Keyword_while" ;
: $$print ." Keyword_print" ;
: $$putc ." Keyword_putc" ;
: DIGIT? 48 58 WITHIN ;
: ALPHA? DUP 95 = SWAP \ underscore?
DUP 97 123 WITHIN SWAP \ lower?
65 91 WITHIN OR OR ; \ upper?
: ALNUM? DUP DIGIT? SWAP ALPHA? OR ;
: INTEGER 0
BEGIN PEEK DIGIT?
WHILE GETC [CHAR] 0 - SWAP 10 * +
REPEAT ;
: ?INTEGER? CR ." Invalid number" CR BYE ;
: ?INTEGER PEEK ALPHA? IF ?INTEGER? THEN ;
: DIGIT .WHERE+ ." Integer " INTEGER ?INTEGER . CR ;
: NAME PAD
BEGIN PEEK ALNUM?
WHILE GETC OVER C! CHAR+
REPEAT PAD TUCK - ;
: IDENT ." Identifier " TYPE ;
: ALPHA .WHERE+ NAME FIND-KW
IF EXECUTE ELSE IDENT THEN CR ;
: ?CHAR? CR ." Character '" EMIT ." ' not recognized" CR BYE ;
: SPACE? DUP BL = SWAP 9 14 WITHIN OR ;
: SKIP-SPACE BEGIN PEEK SPACE? WHILE SKIP REPEAT ;
: CONSUME
SKIP-SPACE
PEEK DIGIT? IF DIGIT ELSE
PEEK ALPHA? IF ALPHA ELSE
PEEK >TOKEN FIND
IF SKIP EXECUTE ELSE GETC ?CHAR? BYE THEN
THEN THEN ;
: TOKENIZE BEGIN CONSUME AGAIN ;
TOKENIZE</lang>
{{out}}
Tested against all programs in [[Compiler/Sample programs]].
=={{header|FreeBASIC}}==
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