SCAN is a keyword used in SAP ABAP programming.This tutorial covers its introduction & syntax details. SCANBasic formSCAN ABAP-SOURCE itab1 TOKENS INTO itab2STATEMENTS INTO itab3.Additions1. … FROM n12. … TO n23. … KEYWORDS FROM itab44. … LEVELS INTO itab55. … OVERFLOW INTO c16. … WITH ANALYSIS7. … WITH COMMENTS8. … WITH INCLUDES9. … WITHOUT TRMAC10. … PROGRAM FROM c211. … INCLUDE INTO c312. … MESSAGE INTO c413. … WORD INTO c514. … LINE INTO n315. … OFFSET INTO n4EffectBreaks down the ABAP/4 source code in the source code table itab1 into tokens according to the rules of the ABAP/4 scanner. The tokens are written – one per line – to the token table itab2 .The token table itab2 must have the structure STOKEN . (If you specify the addition WITH ANALYSIS , the token table must have the extended structure STOKEX .)Normally, comments are filtered out and subordinate source code units (included programs, called macros) are ignored. If you want to include these items, use the additions WITH COMMENTS and WITH ANALYSIS .In addition to classifying the source code by token, the scanner organizes the tokens themselves into statements – using the colon-comma logic to form chain records – and the statement table itab3 contains a statement description on each line. Here, a three-part chain record “a: b, c1 c2, d.” results in three entries “a b,”, “a c1 c2,” and “a d.” in the statement table itab3 .The statement table itab3 must have the structure SSTMNT .The statement classification characters colon, comma and period are not written to the token table itab2 . Instead, the table itab3 contains details about the position of a colon or the type (comma or period and position of the end marker in the statement description.The return code value is set as follows:SY-SUBRC = 0 Source code table is not empty, contains no errors and is broken down into tokens.SY-SUBRC = 1 Source code table is not empty and is broken down into tokens, but at least one include program does not exist (can occur only in connection with the addition WITH INCLUDES ).SY-SUBRC = 2 Source code table itab1 is empty or a blank line range was selected (applies to the additions FROM and TO ).SY_SUBRC = 4 Scanner detects error in source code.SY-SUBRC = 8 Other error or RABAX in scanner.The fields of the structure STOKEN , and thus the columns of the token table itab2 , have the following meaning:TYPE Type of token with possible values:I (Identifier)S (String, i.e. character literal)L (List, enclosed in parentheses)C (Comment)ROW Number of line where token occurs or where it begins (>= 1)COL Offset of first character of token relative to start of line (>= 0)LEN Length of tokenSTR Character string forming the token (or just first part)OVFL Overflow flag for field STR with the following possible values:SPACE (no overflow, token fits completely in field STR )X (overflow, either not resolved (no overflow are specified) or token fits in overflow area c1 ))O (overflow of token and overflow of overflow area c1 )OFF1 Offset in overflow area, iftoken does not fit completely in field STR andan overlfow area c1 is specified andtoken fits completely in overflow area c1 .The fields of the structure SSTMNT , and thus the columns of the statement table itab3 , have the following meaning:TYPE Type of statement with the following possible values:E (Native SQL statement between EXEC SQL andENDEXEC )I ( INCLUDE prog )J ( INCLUDE prog , prog does not exist, canoccur only in connection with the additionWITH INCLUDES )R (Call a macro from table TRMAC )D (Call an internally defined macro with DEFINE )M (Macro definition between DEFINE andEND-OF-DEFINITION )C ( COMPUTE statement, sometimes withoutCOMPUTE as first token)K (Other ABAP/4 key word)N (Blank statement)U (Unknown, non-blank statement)LEVEL Index of source code unit in the level table itab5 (>= 1, if level table specified, otherwise 0)FROM Index of first token of statement in the token table itab2TO Index of last token of statement in the token table itab2 (the end marker of the statement – comma or period – counts as no more then a token)NUMBER Statement counter in a source code unit. Covers all statements, regardless of how many are actually selected – in cases where a key word table itab4 is specifiedPREFIXLEN Number of tokens before the colon (with chain statements >= 1, otherwise 0)COLONROW Line number of colon (with chain statements >= 1, otherwise 0)COLONCOL Column position of colon (with chain statements >= 0, otheriwse 0)TERMINATOR End marker of a statement (normally a period or a comma, but SPACE in the case of native SQL statements and internal macro definitions)TROW Line number of end marker (>= 1, if TERMINATOR <> SPACE , otherwise 0)TCOL Column position of end marker (>= 0, if TERMINATOR <> SPACE , otherwise 0)NotesWhen expanding macro calls, no position specifications are available. The relevant fields in the token table itab2 and in the statement table itab3 are then set to 0.Unlike the usual syntax check, the following are not treated as errors:Comma without preceding colon (the comma then acts as an end marker),Open chain statement sequence at end of source code, i.e. the last statement is closed by a comma, not by a period,Open statement at end of source code, i.e. the last statement is closed neither by a period nor by a comma.To be able to analyze errors without modifying programs, use the additions INCLUDE , MESSAGE , WORD , LINE and OFFSET . These provide information about the errors which have occurred.Addition 1… FROM n1Addition 2… TO n2EffectBreaks down the source code table itab1 into tokens not from start to finish, but only from line n1 to line n2 .The additions FROM n1 and TO n2 must follow specification of the source code table itab1 – in this order.NotesWhen using the start specification n1 , use the addition WITHOUT TRMAC to ensure that there are no unnecessary database accesses to the table TRMAC .The end specification n2 is treated as “soft”, i.e. a statement that begins on a line <= n2 , but ends only on a line > n2 , is not returned completely.If the end specification n2 is split in a chain statment, only the split part up to the next comma is returned completely, not the entire chain statement up to the next period.Negative line specifications are not allowed and result in a runtime error.A line specification of 0 amounts essentially to no specification.If n1 number of lines in source code table, the scanner is not called ( SY-SUBRC = 2).If n1 > n2 and n2 > 0, the scanner is not called ( SY-SUBRC = 2).Addition 3… KEYWORDS FROM itab4EffectDoes not return all statements, only those specified in the key word table itab4 .If the key word table is empty (i.e. it contains 0 lines), all the statements are selected.The lines of the key word table are treated as a character field.To select a native SQL statement or a macro definition, you can specify the pseudo key words EXEC_SQL or DEFINE_MACRO . It makes no difference whether these are intercepted. Native SQL statements and macro definitions are returned as statements (of type E or M whenever the expansion of a macro definition results in more than one statement.If the key word contains a blank line, blank statements are also selected.Addition 4… LEVELS INTO itab5EffectStores details about each edited source code unit (source code table itab1 itself, expanded include programs, expanded macro definitions) in the level table itab5 .Specification of a level table makes sense only with the addition WITH INCLUDES .The level table itab5 must have the structure SLEVEL .The fields of the structure SLEVEL – and consequently the columns of the level table itab5 have the following meaning:TYPE Type of source code unit with the following possible values:P (Program)D (Internal DEFINE macro)R (Macro from table TRMAC )NAME Name of source code unit (name of include program, macro name)DEPTH Current nesting depth of source code unit (>= 1)LEVEL Index of superior (i.e. included or called) source code unit in the level table (>= 1, if DEPTH >= 2, otherwise 0)STMNT Index of superior (d.h. included or called) statement in the statement table (>= 1, if DEPTH >= 2, otherwise 0)FROM Index of first statement of source code unit in the statement table (>= 1)TO Index of last statement of source code unit in the statement table (>= 1)If the source code unit contains include programs or macro calls, the line range [ FROM, TO ] in the statement table also covers the statements in subordinate source code units.Addition 5… OVERFLOW INTO c1EffectIf a token is too large to be stored in the token table in the field STR , it is placed in the overflow area c1 . The offset of the token in the overflow area then lies in the token table in the field OFF1 .Addition 6… WITH ANALYSISEffectBreaks down each token t = a+b(c) according to the logic of the RSYN key word >ANALY into its three components a, b and c.Offset and length of components a, b and c are stored in the fields OFF1 , LEN1 , OFF2 , LEN2 , OFF3 and LEN3 in the token table.If you specify the addition WITH ANALYSIS , the token table itab2 must have the structure STOKEX , so that the fields LEN1 , OFF2 , LEN2 , OFF3 and LEN3 are available.If the whole token exists in the token table, the offset specifications are relative to the token start. If the token is in the overflow area c1 , the offset specifications are relative to the start of the overflow area.Addition 7… WITH COMMENTSEffectReturns comments also, with each individual comment representing a token.NoteThe addition … WITH COMMENTS is unfortunately not supported at present!Addition 8… WITH INCLUDESEffectAlso breaks down subordinate source code units (included programs, called macros) into tokens.You should normally combine the addition WITH INCLUDES with the addition LEVELS INTO itab5 .NoteIf (at least) one included program does not exist, SY-SUBRC is set to 1 and the relevant INCLUDE statement is flagged in the statement table itab3 by the statement type J (instead of I). Otherwise, the breakdown process continues. The level table itab5 contains no entry for include programs that do not exist.If you combine WITH INCLUDES with WITHOUT TRMAC , TRMAC macros are not expanded because the system does not recognize them as subordinate source code units.When macro calls are expanded, no position specifications are available. The fields in the token table itab2 and the statement table itab3 are then set to 0.Addition 9… WITHOUT TRMACEffectIf a statement begins neither with an ABAP/4 key word nor with a DEFINE macro, the system does not check whether this is a TRMAC macro, but assumes an unknown statement. (Unknown statements are flagged in the statement table itab3 with a U in the field TYPE .)To avoid unnecessary database accesses to the table TRMAC , you should use the addition WITHOUT TRMAC whenever you want to assume that the source code to be scanned contains unknown statements. Unknown statements are particularly likely to occur if you use the addition FROM n1 . In this case, the scanner does not start at the beginning of the source code, but from a specified point.NoteIf you use WITHOUT TRMAC with WITH INCLUDES , TRMAC macros are not expanded because the system does not recognize them as subordinate source code units.Addition 10… PROGRAM FROM c2Addition 11… INCLUDE INTO c3Addition 12… MESSAGE INTO c4Addition 13… WORD INTO c5Addition 14… LINE INTO n3Addition 15… OFFSET INTO n4EffectThe above additions have the same meaning as the those for the SYNTAX-CHECK statement: c2 is an input field for a program name to be assigned to the source code, while the fields c3, c4, c5, n3 and n4 are output fields in case an error occurs.To be able to analyze errors without modifying programs, use the additions INCLUDE , MESSAGE , WORD , LINE and OFFSET . These provide information about the errors which have occurred.