Word Replacement

rascal-0.40.17

Synopsis

Replace words in a string.

Description

Suppose you are a book editor and want to ensure that all chapter and section titles are properly capitalized. Here is how to do this.

Examples

import String;

str capitalize(str word:/^<letter:[a-z]><rest:.*>/) 
  = "<toUpperCase(letter)><rest>";

default str capitalize(str word) = word;

test bool capitalize1() = capitalize("1") == "1";
test bool capitalize2() = capitalize("rascal") == "Rascal";

@synopsis{Version 1: capAll1: using a while loop}
str capAll1(str S)      ❷  
{
 result = "";
 while (/^<before:\W*><word:\w+><after:.*$>/ := S) { 
    result = result + before + capitalize(word);
    S = after;
  }
  return result;
}

test bool tstCapAll1() =  capAll1("turn this into a title") == "Turn This Into A Title";

@synopsis{Version 2: capAll2: using visit}
str capAll2(str S)      ❸  
{
   return visit(S){
    case /^<word:\w+>/i => capitalize(word)
   };
}

test bool tstCapAll2() = capAll2("turn this into a title") == "Turn This Into A Title";

• ❶ We start by introducing a helper function capitalize that does the actual capitalization of a single word. See Regular Pattern for details about regular expression patterns. Next we give two versions of a capitalization function for a sentence:

• ❷ capAll1 uses a while loop to find subsequent words and to replace them by a capitalized version.

• ❸ capAll2 uses a Visit to visit all words in the sentence and replace them by a capitalized version.

Here are some examples:

rascal>capitalize("rascal");
str: "Rascal"
---
Rascal
---
rascal>capAll1("turn this into a capitalized title")
str: "Turn This Into A Capitalized Title"
---
Turn This Into A Capitalized Title
---
rascal>capAll2("turn this into a capitalized title")
str: "Turn This Into A Capitalized Title"
---
Turn This Into A Capitalized Title
---