rete - REcursive Template Engine
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1. a single dash the output of the child template is inserted in the output of the parent template this feature can be considered as a form of include In the variables section the parent template can set up the global variables of the child template It is a comma separated list of name value pairs pairs or single names When name value is used the given name will be a global variable in the child template initialized with the corresponding value while listing a single name will be the same as Chapter I User s manual if name name was written that is the variable named name in the parent template is passed to the child template Except for this last feature the variable list of create is very similar to the argument of command set Note the variable list may be empty in this case an empty should be used 1 4 2 3 eval Eval takes a string literal argument executes it as a rete template script and substitues the output For example eval expr 1 2 will be substituted with 3 0000 of course in this case a plain expr 1 2 would result in the same output Eval may be useful to call create and use the output of templates as string literals 1 4 2 4 expr Altough rete is not designed for doing calculations it provides expr which evaluates a mathematical expression and the result is substituted Currently the following operations are supported e is addition e is substraction e is multiplication e 1s divisio2. are available e db txt loads text databases into variables and arrays e geo geographic functions math basic arithmetics e string string manipulation e system system calls e vars advanced variable manipulation 1 4 3 1 Package db txt This package can parse simple text database files and set rete global variables including arrays accordingly The file format is simple Example 1 7 db_txt database file this is a comment vl one commentl v2 two comment2 oo Sal first third fourth 55a2 first second third empty o 6 oo oo oo v3 three comment3 Chapter I User s manual Lines starting with a hashmark are comments The next two lines will create variable v1 with value one and v2 with value two SCOMMENT__v1 and SCOMMENT v2 are also created and loaded with strings com mentl and comment2 respectively A line starting with loads an array whose name is given after the Each line will become a new element of the integer indexed array after starting and trailing white spaces have been stripped off A single 9090 line terminates array loading mode and returns to normal variable loading 1 4 3 1 1 db txt usef file name Call db txt use will load the text db file called file name into the current global variable namespace 1 4 3 2 Package geo This package provides functions for geographic calculations 1 4 3 2 1 coord offset base point distance off
3. dynamic content wrapped in markers Dynamic parts can do calculation can start recursive processing of further templates can import data from files 1 4 Reference manual Rete template processing reads one input file and generates one output file and can run processing of subtemplates recursively There are two modes of operation copy and execute When a template file is opened copy mode is set In copy mode the output is verbatim copy of the input Template script blocks are wrapped in and markers when rete reaches an script block open sequence percent bracket it switches to execute mode and switches back to copy mode only when the closing sequence brakcet percent is reached Chapter I User s manual In execute mode the input is split into tokens and the tokens are evaluated Tokens may be strings which are copied to the output after processing of some escape sequences see below or rete builtin instructions or external commands Tokens are separated by whitespaces As a common practice each instruction starts in a new line and indenting similar to the one used in C should be applied This section is a reference manual for the execute mode and covers escape sequences all builtin instructions and generally the features of the rete template scripting language 1 4 1 String literals escape sequences Words which are neither builtin commands nor external function calls are threated as string literals and are copied to
4. the output Whitespaces are ignored n It is possible to protect string literals with double guotes threated as a single string literal including white spaces In this case everything between the double guotes is Example 1 3 Using string literals template This is a te xt x te and xt are string literals the space between them will be ignored x We can x space is preserved x mo x a single space protected with dobuble quotes is a string literal protect spaces and then we can go on with verbatim text Example 1 4 Using string literals output This is a text We can protect spaces and then we can go on with verbatim text Text outside of rete template scripting is copied without further processing However string literals inside the scripting blocks are processed and escape sequences are substituted Currently the following escape sequences are in use e M tab character M newline character e wi double quote character 1 4 2 Rete builtins Rete is a compact language with minimal amount of builtins Task specific or acceleration or system dependent commands are implemented in dynamic loadable plugins as external commands see later Builtin commands are groupped in 4 groups e variables set expr and operators Chapter I User s manual e control if for foreach switch template generation create e misc eval load All builtin commands are described below in al
5. ces the other 8 subpage html files the other is the template for a single subpage Example 1 1 index tmpl lt html gt lt body gt lt H1 gt Rete templat xample lt H1 gt lt UL gt s Change numberic format print integers x format 0 for n 0 n lt 8 n inc n 1 Generate a link on the index page x lt LI gt lt a href n html gt subpage n lt a gt lt LI gt n x Generate the subpage referenced from the index page x create subpage tmpl gt Sn html name n do lt UL gt lt body gt Chapter I User s manual lt html gt Example 1 2 subpage tmpl lt html gt lt body gt lt H2 gt This is subpage name lt H2 gt lt body gt lt html gt The above example is used as rete index tmpl gt index html all files will be generated in the current working direc tory When the subprocess of generating a subpage is started the global variables of the subprocess are set as defined in the parent template in this case name 1 3 Template scripting summary Core features verbatim copy of the input to the output intepreting template scripts wrapped in processing further template files normally generating new output files controls if switch loops variables numbers text arrays External commands read database from file to array math functions Language summary a template looks like the output expect for
6. less else greater than 2a In rete the if statement is similar to the one on C There s an expression in the braces the syntax is the same as in the argument of an expr call If the expression is evaluated to true the then section is run otherwise the else section is choosen The else section may be omitted 1 4 2 8 load Load is used to load rete plugins which will provide external commands The syntax is simple load name where name is the name of the package without leading rete 1 4 2 9 set Set is used to create variables and change the value of variables A single set command can perform these action on arbitrary amount of variables The syntax of set is the following set namel valuel name2 value2 na meN valueN where each nameX is the name of a variable and the corresponding valueX is the new value of the variable 1 4 2 10 switch Example 1 6 switch switch n case one d 21 case two d 2 case three 3 case four 4 eb ech es default none Chapter I User s manual The above example demonstrates the syntax of switch Unlike in C cases are not fall trough For a given input n in this example exactly one of the cases or the default will run 1 4 3 Rete packages plugins With command load the user may load rete plugins to access external commands This section is a reference to the packages shipped with rete Currently the following packages
7. n e lt evaluated to true if the first operand is less than the second e lt evaluated to true if the first operand is less than or equal to the second gt evaluated to true if the first operand is greater than the second e gt evaluated to true if the first operand is greater than or equal to the second e evaluated to true if the two operands are equal l evaluated to true if the two operands are not equal e lis logical not e amp amp is logical and e Ilis logical or For example expr 3 1 2 will be substituted by 9 Note simply writing 1 1 in the template script part will not result in 2 without wrapping it in an expr 1 4 2 5 for In rete the syntax of for is very similar to the one in C but less general for initial set while loop set body Initial set is a single name value pair that initializes a variabe The while part is evaluated as an expression see expr the loop ends when the result of the expression is false Loop set is run at the end of each cycle and is similar to the initial set argument a single name value pair Chapter I User s manual 1 4 2 6 foreach Foreach can be used to consider each element of an array either linear or hash The syntax is foreach index in array where index is a variable name and array is the name of the array Index will take each existing index value that presents in the array in random order 1 4 2 7 if Example 1 5 if 1 is if 1 lt 2
8. phabetic order after the section about variables 1 4 2 1 Variables Variables are referenced by their names A name must be a valid identifier starting with a letter containing any amount of letters numbers and underscores A dollar sign and the name of the variable is substituted with the value of the array for example if the value of variable breakfast is string literal ham and eggs writing breakfast in the script is the same as writing string literal ham and eggs Of course the value of a variable can be changed any time using command set Variable names may contain nonalphanumeric values or even white spaces In this case the whole name must be protected with signs after the dollar sign For example long name with spaces is a valid variable name Variables are either scalar or arrays arrays are indexed using indices between braces Using such braces after the dollar sign would break the rule of using alphanumeric characters only so referencing array elements implies using protection my_array 42 An array is either a linear array when indexed by numbers or a hash table when indexed by string literals Rete will automaticly decide about using a linear array or a hash table the user doesn t need to worry about choosing one However once an array type is decided as of the current version rete will not convert the array to the other type A rule of thumb is as long as an array is indexed only by integers it
9. pied verbatim while commands between and markers are interpreted as template scripts Template scripts can request another file to be generated This normally involves processing another template file into another output file but appending to the current output and or reprocessing the current template are both possible Such recursive template processing should be regarded as a child process that may inherit variables from the caller Note rete doesn t actually fork or create threads everything is done in a single process single thread manner Since the template script language provides loops arrays and branching we often use the first template as a starting point or config file or run control file that can decide which output files should be generated from which templates It s also common that we generate a large number of files using a small number of templates Template scripting is divided into two parts internal commands and external extension commands There are only a few internal commands a small infrastructure on which external commands can be built This infrastructure pro vides data storage run control loops branches and the above mentioned recursive template processing External commands are like function calls which have full access over the variables of the current running template processor 1 2 Template scripting example The following example has two templates one of which generates an index html that referen
10. r Strip leading and trailing white spaces and replace any other white space with _ in str and return the result 1 4 3 4 4 upper str Converts str to all uppercase and return the result 1 4 3 4 5 lower str Converts str to all lowercase and returns the result 1 4 3 4 6 strcomp str1 str2 Compares strings str and str2 and returns 0 if they are equal or their alphabetic order if not Note it s a call to stremp 3 1 4 3 4 7 split str arr sep Splits str into fields using sep and creates loads array named arr with the fields The array will be integer indexed from 0 Chapter I User s manual 1 4 3 5 Package system This package provides system calls mostly for manipulate the file system 1 4 3 5 1 sys_mkdir name perm Creates directory name with permissions perm optional If permissions is given it must be a number in decimal octal or hexadecimal format as documented in strtol 3 NOTE on windows permission is ignored 1 4 3 5 2 sys access name mode Checks access of file name against mode and return 1 if it was OK The following values are accepted for mode e R OK the file is readable e W OK the file is writable e X OK the file is executable F OK the file is a plain file 1 4 3 5 3 sys system cma Call popen 3 to execute cmd in the background and returns the full output of the run 1 4 3 6 Package vars The vars package provides basic functions for guerying and manip
11. rete REcursive Template Engine Tibor Palinkas igor2rete at inno dot bme dot hu Istvan Sandor sandori at rht dot bme dot hu rete REcursive Template Engine by Tibor P link s and Istvan Sandor Table of Contents I MT ET 1 1 1 Introduction to template Scripting sss Pair a a nan 1 1 2 KEE TEE 1 1 3 Template scripting summary 20 0 ee eee eee cee ceseeeeeeeceeeeseeceesaeesceeceaeeaeecaecaaesaesaeceeceeeeseseeeeaessasaesaeeneeeeeeeeegs 2 14 Reference manual ee EE 2 1 4 1 String literals escape seguences ooooonoonoonooono cae o ns o nn 3 UE NEU EE 3 WA en b EE 4 VA 22 CLANS R teneanveaeveib eee 4 VAD 3 OVA E E E EE E 3 UE DAs E 5 UA De EE 5 1A 2 0 te EE 5 NAD WEE 6 1 4 28 EE 6 VAD ET 6 VA DOs SILON EE 6 14 35 Rete packa E EE 7 VAS Te PAaCk age db ARC EE 7 UE e2 PAC KAP e SCO EE 8 1 A 3 3 Package Mati EE 8 1 434 Packat Stino aise cscssssestesueiss sbcesapeiosadsoissateeskedoiyssbsosseesieedsnaGessphionbetaspligendbecnestesspedonadeepessesers 9 14 3 3 Package SYST M sde ait eysctevsduseeunsus tests a lia 9 1 4 3 6 Package Var c sescsseiesissastdevsdesescvsubssousessanedenges4epsaesvaphstayusbeanicasisbopescesapevoayesdasasneensesibecesee dooney 10 iii List of Examples Chapter 1 User s manual 1 1 Introduction to template scripting Rete is controlled by template files On start rete opens a single template file for processing While processing a template file normal text is co
12. set direction Calculate coordinates of a geographic point given by a base point a distance offset and a direction The base point must be given as a string like this N12 34 56 78 E 12 34 56 78 distance offset is the distance in meters direction is the direction in degrees N 0 E 90 S 180 W 270 1 4 3 3 Package math This package provides mathematical functions 1 4 3 3 1 inc value Increase value by one and return the result Useful in cycles to avoid a long expr which would be also slower 1 4 3 3 2 dec value Decrease value by one and return the result Useful in cycles to avoid a long expr which would be also slower 1 4 3 3 3 alog value Return the logarithm of value 1 4 3 3 4 asgrt value Return the sguare root of value Chapter I User s manual 1 4 3 3 5 apow base pwr Return base raised to the power of pwr 1 4 3 3 6 format num_digits Changes the standard numeric output format any time a number is printed num digits digits will be used after the decimal point 1 4 3 4 Package string This package provides functions for string manipulations 1 4 3 4 1 strip str Strip leading and trailing white spaces fromstr and return the resulting string 1 4 3 4 2 field str fieldno sep Extract a specific field of a sep separated string str Argument fieldno selects the field counting from 0 For example consider str alblc field str 1 I will return b 1 4 3 4 3 canon st
13. ulating variables e g checking the existence emptyness of a variable deleting a variable etc 1 4 3 6 1 present variable name return 1 if a variable exists otherwise return 0 load vars set x 1 if present x there is a variable named x n x this will show up in the output x if present y there is a variable named y n x this won t x else variable named y does not exist n this will be printed instead x 10 lt oo 1 4 3 6 2 isempty variable name return 1 if a variable is nonexistent or an empty string array or hash otherwise return 0 s load vars set x se y hello if isempty x x is empty n x this will show up in the output if isempty y v is empty n this won t x else y is Sy n x this will be printed instead M 1 4 3 6 3 length variable name return the length of a string or the number of elements in an array or hash 1 4 3 6 4 uniq element array insert element into array if it s not already present in array oo load vars set unig i x does not insert i Wy is Sx ny unig j x x insert bi J x s is Sx Wyn Chapter I User s manual 11 Chapter I User s manual 1 4 3 6 5 delete variable_name delete a variable after this call present variable_name will return false 0 12
14. will be a linear array This implies that if the first few indices are numbers the array becomes a linear array and later string literal indices can not be added This bug will be fixed later A special feature of linear arrays is auto indexing When a new element is added with an empty index using rete takes the last index of the array increases it by one and uses this number as the new index This makes it easy to grow an array without needing to store the last index or count the elements This feature does not work with hash arrays Some rete commands like set for or foreach will require variable names A variable name is the name of the variable without the dollar so variable substitution is not performed Using a dollar sign there causes indirect variable usage For example if the value of variable name is breakfast then usign name where a variable name is expected will cause variable breakfast to be used as the variable name 1 4 2 2 create Create causes rete to suspend the interpreatation of the current template and start interpreting another template called the child template When interpreting the child template is finished rete resumes interpreting the parent template The parent template sets up the child template s global variables This syntax of create is create template gt output variables Argument template is the name of the template file and output is the name of the output file If the output file is
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