prototype-3x5/src/words.ts

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/**
* A word whose value is text with provenance- this literal value appeared in the source
* code, and was not the result of any backslash, variable, or command substitutions.
*
* This provides a level of intentionality that commands can use to distinguish switches:
*
* ```tcl
* puts -stderr text ;# -stderr can be interpreted as a flag and is not part of the message to print
* puts "-stderr" text ;# -stderr is not a flag, but is part of the message to print
* puts $var text ;# The value of $var is part of the message to print, even if the value happens to be "-stderr"
* ```
*/
export type EnchantedWord = {
enchanted: string;
};
/**
* A word whose value is plain text, with no special provenance.
*/
export type TextWord = {
text: string;
};
/**
* A word whose value is "safe" HTML using allowlisted elements/attributes/styles,
* suitable for inclusion in HTML output with no escaping.
*/
export type HtmlWord = {
html: string;
};
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export type TextPiece = TextWord;
export type VariablePiece = { variable: string };
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export type ScriptPiece = { script: Script };
export type InterpolatedPiece = TextPiece | VariablePiece | ScriptPiece;
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/**
* A word whose value needs to be determined by evaluating some combination of variable and command
* substitutions, and concatenating the results with any literal spans.
*/
export type InterpolatedWord = {
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pieces: InterpolatedPiece[];
};
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// safely concatenate text pieces, converting as needed
export function Concat(left: TextPiece, right: TextPiece) {
return { text: left.text + right.text };
}
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function IsTextPiece(piece: InterpolatedPiece | undefined): piece is TextPiece {
return piece ? "text" in piece : false;
}
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export function SimplifyWord(
pieces: InterpolatedPiece[]
): InterpolatedWord | TextWord {
const consolidated: InterpolatedPiece[] = [];
for (const piece of pieces) {
const top = consolidated[consolidated.length - 1];
if (IsTextPiece(top) && IsTextPiece(piece)) {
consolidated[consolidated.length - 1] = Concat(top, piece);
} else {
consolidated.push(piece);
}
}
if (consolidated.length == 0) {
return { text: "" };
} else if (consolidated.length == 1 && IsTextPiece(consolidated[0])) {
return consolidated[0];
} else {
return { pieces: consolidated };
}
}
export type Word = EnchantedWord | TextWord | HtmlWord | InterpolatedWord;
export type Command = Word[];
export type Script = Command[];